Supply chain traceability and counterfeit detection of COVID-19 vaccines using novel blockchain-based Vacledger system

Abstract

We propose a novel framework, Vacledger, for supply chain traceability and counterfeit detection of COVID-19 vaccines using a blockchain network. It includes four smart contracts on a private-permissioned blockchain network for supply chain traceability and counterfeit detection of COVID-19 vaccine, more specifically to (i) handle the rules and regulations of vaccine importing countries and provide authorization for cross the borders (regulatory compliance and border authorization smart contract), (ii) register new and imported vaccines in the Vacledger system (vaccine registration smart contract), (iii) find the number of stocks that have arrived in the Vacledger system (stock accumulation smart contract), and (iv) identify the exact location of the stock (location tracing update smart contract). Our results show that the proposed system keeps track of all activities, events, transactions, and all other past transactions, permanently stored in an immutable Vacledger connected to decentralized peer-to-peer file systems. We observe no algorithm complexity differences between the proposed Vacledger system and existing supply chain frameworks based on different blockchain types. In addition, based on four use cases, we estimate our model’s overall gasoline cost (transaction or gas price). The Vacledger system empowers distribution companies to manage their supply chain operations effectively and securely using an in-network, permissioned distributed network. This study employs the COVID-19 vaccine supply chain (the healthcare industry) to demonstrate how the proposed Vacledger system operates. Despite this, our proposed approach might be implemented in other supply chain industries, such as the food industry, energy trading, and commodity transactions.

1. Introduction

The rising importance of COVID-19 vaccines in mitigating the adverse consequences of the crisis impacts and returning the world to civilization cannot be underestimated. Globally, there have been more than 663,242,233 COVID-19 cases and more than 6,691,208 fatalities (Worldometers, 2023), bringing many countries’ economies and organizations to their knees, and hindering growth and development. Prior to the introduction of the COVID-19 vaccine, the issue of counterfeits was widespread in many developing nations (Amankwah-Amoah, 2022). The fast spread of the virus across national boundaries has made it virtually impossible for governments to contain and manage the epidemic. It has substantially affected global public health, the economy, and society. The World Health Organization (2023) (WHO) has designated the COVID-19 pandemic a Public Health Emergency of International Concern (PHEIC).

Meanwhile, thousands of fake vaccines (Interpol, 2023) are being produced and delivered anonymously. Counterfeit vaccines are unregulated and incorrectly labeled vaccines whose identity and origin are hidden or intentionally misrepresented. Inadequacies in these vaccinations include false labeling, insufficient or incorrect component amounts, improper or absence of packaging, and the results of uneven vaccine distribution (Amankwah-Amoah, 2022).

To increase profit, fake vaccine businesses prevent communication between manufacturers and patients. A traceability mechanism is required to prevent the manufacture of fraudulent vaccines. The UNICEF (2023) and World Health Organization (2023), the The Global Alliance for Vaccines and Immunizations, World Health Organization (2023) Secretariat, and other partners are working together to develop and deploy adaptable global resources to support the introduction of the COVID-19 vaccine (World Health Organization, 2023). This study focused on developing smart contracts for tracking to identify the exact location of vaccine stock, vaccine registration, vaccine stock, and regulatory compliance and border authorization (Global borders and state borders). This is achieved by using IBM’s Hyperledger Fabric (Hyperledger, 2018) tool-set in a blockchain.

1.1. COVID-19 vaccines

One option to utilize blockchain for supply chain traceability is to store information regarding vaccinations on a blockchain ledger, such as the manufacturer, batch number, expiry date, and storage and handling conditions. Authorized parties, such as healthcare practitioners, regulatory bodies, and supply chain partners, may access this information to verify the authenticity and integrity of the vaccines.

There are a few vaccines against the coronavirus (COVID-19): Pfizer BioNTech (AstraZenec, 2023, Moderna, 2023, Novavax, 2023, Pfizer, 2023), and Sanofi/GSK (Sanofi, 2023). However, the current situation shows that only a few vaccines can survive and fight against the coronavirus. The progress has been great so far with AstraZenec, 2023, Johnson and Johnson, 2023, Moderna, 2023, and Pfizer (2023). There are several vaccines against COVID-19: AstraZenec, 2023, Moderna, 2023, Novavax, 2023 and Pfizer (2023) , and Sanofi (2023). However, the current situation shows that only a few vaccines can be preserved economically and are effective against the coronavirus (World Health Organization, 2023). To date, the progress has been positive for AstraZenec, 2023, Johnson and Johnson, 2023, Moderna, 2023, and Pfizer (2023).

1.2. Logistics Internet-of-Things (L-IoT)

Logistics is one of the practical uses of the Internet of Things. Logistics Internet-of-Things (L-IoT) combines physical things or assets with the internet and uses sensors, software, and connectivity to gather and send location, status, and condition data. This technology enhances supply chain visibility and transparency in logistics, allowing for more informed decision-making and smoother operations. The L-IoT has the potential to transform supply chain management by providing real-time insight into the location, status, and conditions of goods (Golpîra et al., 2021, Ivankova et al., 2020, Milić et al., 2023, Winkelhaus and Grosse, 2020). Managing the supply chain for COVID-19 vaccines may benefit from the L-IoT for increased visibility into inventory and protection against counterfeits. Logistics teams can check the temperature, humidity, and other environmental conditions that may impact vaccination effectiveness by employing IoT sensors to track the transportation and storage of vaccine shipments. This information may be sent in real-time to blockchain-based smart contracts, which can subsequently be used to confirm the authenticity of vaccinations and guarantee that they have not been tampered with or diverted. Moreover, L-IoT may enhance routing, decrease transit times, and reduce the chance of loss or theft. The L-IoT can assist the global effort to prevent the COVID-19 pandemic by facilitating the delivery of vaccinations securely and efficiently by increasing supply chain visibility and transparency.

1.3. Policy, theory, and practice in supply chain management

The literature has highlighted several theoretical, practical, and policy implications of supply chain management. When we consider the COVID-19 supply chain,

• (i)How governments and other stakeholders may influence and control supply chain operations to accomplish societal objectives are what we mean when we talk about the policy implications (Khorasani, Sarker, Kabir, & Ali, 2022) of supply chain management. Companies may be incentivized to adopt sustainable supply chain practices, and social and environmental concerns like worker rights and pollution can be addressed by government legislation.
• (ii)Supply chain management has theoretical significance since it deepens our knowledge of product and service production, distribution, and consumption. Supply chain management studies have helped us learn things like how to manage global supply networks better, how to optimize our decision-making in the face of uncertainty, and how businesses may increase their competitiveness (McDougall, Wagner, & MacBryde, 2022) by integrating their supply chains.
• (iii)The practical implications of supply chain management are how businesses use this information to advance their operations and gain a market advantage. Many organizations are adopting the fundamentals of supply chain management to save costs, boost productivity, and satisfy customers.

Supply chain management’s policy, theoretical, and practical implications have far-reaching effects on corporate operations, economic growth, and social well-being.

1.4. Research gap

Despite the growing interest in utilizing blockchain technology for COVID-19 vaccine supply chain (vaccine ledger) traceability and counterfeit detection, various research gaps remain unaddressed. Firstly, there is a lack of research into how the vaccine ledger system can provide regulatory compliance and border authorization for the international transportation and distribution of COVID-19 vaccines. Secondly, it is necessary to establish smart contracts that handle compliance aspects, regulations, and processes unique to the COVID-19 vaccine supply chain. In addition, the feasibility of incorporating L-IoT technologies for tracking and monitoring the vaccine supply chain has not been thoroughly investigated. This study can examine further how L-IoT can be utilized for vaccine registration, stock build-up, and tracking. In addition, it is necessary to explore the difficulties associated with the domestic production and importing of COVID-19 vaccines and how the vaccine ledger can help these procedures. Finally, it is essential to establish a deployment strategy for the vaccine ledger and undertake a risk assessment to detect any system vulnerabilities. Addressing these research gaps can aid in developing a more robust and efficient vaccine supply chain management system.

1.5. Motivations and contributions

Eliminating third-party suppliers increases supply chain transparency and dependability. These features allow tracking and surveillance. Supply chain data may determine a transaction’s status and stock transfer. A blockchain facilitates tracking information (Arumugam, Deepa, Sreekanth, Arun, & Nilesh, 2021). According to the health sector, counterfeit COVID-19 vaccines are causing severe health problems. According to the World Health Organization (2023), counterfeit vaccines are unregulated and mislabeled, and their origins and contents are hidden or intentionally misrepresented. A single supply chain can be used to make and distribute several fraudulent vaccines. This study uses a blockchain network to create a novel framework, Vacledger, for supply chain traceability and counterfeit detection of COVID-19 vaccinations.

Using blockchain-based smart contracts, we track Vacledger- recorded COVID-19 vaccinations to boost the supply chain transparency. The main contributions of this paper include the following.

• (1)We develop a novel private-permissioned blockchain-based Vacledger system for supply chain and logistics IoT traceability and counterfeit detection of COVID-19 vaccines.
• (2)
  We develop smart contracts to manage border authorization, regulatory compliance, policy, theory, and practice in supply chain management; registering imported and newly developed vaccines; stock accumulation; and location tracking (worldwide or zone-wise distribution):

  • •
    Regulatory Compliance and border authorization Smart Contracts (RCBASC): Regulatory compliance and border authorization smart contract (RCBASC): This was created to manage vaccine importation laws. Before starting the vaccine registration procedure, companies importing vaccines must be acquainted with relevant product safety regulations. For this, both parties (the export vaccine country and the import vaccine country) have agreed to the terms of their agreements. Supply chain management is impacted, and regulatory compliance is increased due to entering nations or countries’ states.
  • •
    Vaccine Registration Smart Contract (VRSC): This was created to register manufactured and imported vaccines in the Vacledger system. Vaccines are sent to the consignment procedure after registration. Those vaccine data are recorded in this smart contract.
  • •
    Stock Accumulation Smart Contract (SASC): This was created to determine the number of stocks entering and leaving the Vacledger system. After the registration process in the VRSC, the SASC continually updates the vaccine amounts.
  • •
    Location Tracing Update Smart contract (LTUSC): This was developed to identify the exact location of the stock. Vaccines are distributed worldwide or by zones. Knowing where the stock is currently located is critical, and this contract helps to find it.
• (3)We estimate the total gasoline cost (transaction cost or gas price) based on four realistic scenarios.
• (4)We analyze the proposed Vacledger system based on algorithm complexity, cost estimation, and safety assessments.
• (5)We implement the proposed blockchain-based Vacledger system within the healthcare industry to encourage stakeholders to participate in verifying and validating supply chain transactions.

1.6. Structure of the paper

The remainder of the paper is organized as follows (Fig. 1). Section 1 highlights the previous finding of supply chain traceability in different industries. Section 3 illustrates the model description of blockchain-based smart contracts and Section 4 presents the proposed vaccine traceability structure, Vacledger. Section 5 illustrates the results and performance evaluation of this study. Section 6 demonstrates the findings of the study, discussion, and elaborates on Smart Contract implementation challenges. Section 7 concludes the paper.

Fig. 1.

Outline of our study.

2. Related work

2.1. Logistics Internet-of-Things (L-IoT)

A considerable amount of systematic reviews has been published on Logistics Internet-of-Things (L-IoT) (Golpîra et al., 2021, Winkelhaus and Grosse, 2020). With the rise of the COVID-19 pandemic, the importance of L-IoT in supply chain management has increased, particularly in the delivery of vaccinations. There have been numerous investigations (Golpîra et al., 2021, Milić et al., 2023) into how L-IoT may be used for tracking in the supply chain. These analyses have emphasized the potential cost savings of this technology, its enhanced inventory management accuracy, and supply chain visibility.

L-IoT has also been investigated for potential uses in vaccine distribution in the pharmaceutical industry. During the COVID-19 pandemic, L-IoT has been crucial to keeping vaccine delivery safe and effective. Ali and Khan (2023) introduced a decision-making model for evaluating IoT platforms that fits the logistics and transportation process of the COVID-19 vaccine.

Ivankova et al. (2020) argued that the IoT would cause a considerable transformation in logistics over the next decade. This generates new economic advantages by reducing the cost of device components, boosting the speed of wireless networks, and improving the network’s capacity to accept data. The work focuses on deploying the IoT in logistics, real-world instances of its usage by transport businesses, and the development of new technologies.

The L-IoT has been used to monitor temperature and other environmental factors while vaccines are transported and stored. It has also ensured that vaccines get from the manufacturer to the consumer safely and on time. The L-IoT is a relatively new method of real-time monitoring and controlling logistics processes (Golpîra et al., 2021, Winkelhaus and Grosse, 2020) using a network of networked sensors and devices. This technology’s value in maintaining supply chain efficiency, transparency, and traceability has grown.

2.2. Blockchain technology

Blockchain technology has the potential to be implemented in a variety of supply chain applications. One potential application of blockchain in the supply chain is to increase transparency and traceability. Utilizing a decentralized and transparent ledger allows for tracking the movement of goods and materials through the supply chain in real-time, improving efficiency and decreasing the risk of errors or fraud. Several attempts (Agrawal et al., 2021, Baralla et al., 2021, Behnke and Janssen, 2020, Feng et al., 2020, Halgamuge and Guruge, 2021, Kuhn et al., 2021, Musamih et al., 2022, Saurabh and Dey, 2021, Song et al., 2021, Uddin, 2021), have been made in this direction to use blockchain in the supply chain industry for various applications.

Yadav, Shweta, and Kumar (2023) analyzed blockchain-based vaccine supply chain adoption barriers in the Indian context. The study explored blockchain capabilities and supply chain challenges to investigate how the new technology can transform vaccine distribution. They emphasized the potential of blockchain technology to address vaccine distribution challenges in India, such as cold chain management, inventory control, and vaccine wastage. The study evaluated the adoption barriers and challenges of the blockchain-based vaccine supply chains in India, including technical, operational, and regulatory barriers.

Musamih et al. (2022) proposed a blockchain-based smart-contract solution for reducing COVID-19 vaccine waste in domestic environments despite still needing to incorporate real-time vaccine tracking.

Blockchain technology for COVID-19 vaccine supply chain traceability and counterfeit detection will assist in guaranteeing that vaccines are correctly kept, transported, and delivered and that they are legitimate and not counterfeit. Smart contracts are blockchain-based programs that execute when certain criteria are satisfied.

2.3. Supply chain traceability

In the supply chain, blockchain might be used to simplify the flow of information and documents between stakeholders. For instance, blockchain may be used to securely store and distribute crucial documents such as contracts, invoices, and shipping records, streamlining procedures, and reducing the likelihood of errors or misunderstandings.

Ma, Shi, and Kang (2023) performed an empirical study to assess the influence of digital transformation on the pharmaceutical industry’s sustainable supply chain performance. Using SPSS26.0 and AMOS24.0, the study assessed the function of information exchange and traceability as mediators. Their purpose was to facilitate the pharmaceutical supply chain’s management of digital transformation and sustained supply chain performance improvement.

Sim, Zhang, and Chang (2022) proposed a printed encrypted 2D data matrix on product packaging called eZTracker digital ID to employ blockchain technology in the pharmaceutical supply chain for end-to-end traceability and counterfeiting. However, it does not adopt dynamic changes like smart contracts, which can provide greater flexibility and automation in supply chain management. Further research is needed to evaluate the effectiveness and adoption of blockchain solutions in real-world settings.

Vishwakarma, Dangayach, Meena, Gupta, and Luthra (2022) suggested that the rapid development of patient-centered medical technology will require precise forward and reverse logistics, which cannot be achieved without supporting supply chain management traceability. The authors proposed that digital transformation will add momentum to innovation in the pharmaceutical supply sector, including business models, product processes, and organizational structures. The study emphasized the importance of traceability in supporting the pharmaceutical supply chain to achieve sustainable supply performance.

Uddin (2021) introduced Medledger for the supply chain of the drugs industry. He developed three smart contracts: a drug registration contract, a consignment accumulation contract, and a transaction update contract. A few studies examined (Behnke and Janssen, 2020, Feng et al., 2020, Song et al., 2021) the technology and performance ability of a blockchain in a supply chain for the agri-food industry. In addition, Feng et al. (2020) examined the data tracking in the blockchain’s quality, cost, logistics traceability, and tax consequences. The smart contracts of this system are based on IoT monitoring data.

In 2021 (Kuhn et al., 2021) developed a blockchain system based on Ethereum to examine the traceability needs and liability implications of the automobile manufacturing supply chain for trustworthy and transparent data exchange throughout autonomous vehicle production operations. In contrast, Mangla et al. (2021) has explored the social effects of blockchain technology in the food supply chain of the dairy industry.

2.4. Security and privacy

Further, Qiu and Zhu (2021) suggested a vaccine anti- counterfeiting traceability system that combines public and private chains to protect patient privacy, private chains, in particular, store vaccination records. Traceability emphasizes production, inspection, storage, transportation, and injection. To avoid unauthorized access to a public Ethereum blockchain, participants must be permitted to write data associated with the agri-food supply chain. Baralla et al. (2021) developed smart contracts for certification, distribution, and production. In a recent work (Rajesh, 2023), the Grey Impact Analysis is proposed as a tool for analyzing the influence relations among a collection of parameters when there are several answers. Using this technique, researchers, especially in the marketing and supply chain fields, may investigate challenges that can be addressed using the GINA methodology.

Numerous prior research (Hosseini Bamakan et al., 2021, Kouhizadeh and Sarkis, 2018, Sanka et al., 2021) have revealed data privacy and security concerns associated with blockchain technology. Despite the potential advantages of blockchain for healthcare and pharmaceutical supply chains, the technology is not totally immune to cyberattacks and data theft. This vulnerability may result in the abuse of sensitive medical data and raises data privacy issues. The authors emphasized the necessity for more study and development of blockchain-based privacy and security solutions for the health sector.

2.5. Governance

In addition, Saurabh and Dey (2021) noticed that the order of importance and usefulness in the wine supply chain, disintermediation traceability, price, trust, regulatory compliance, and coordination and control could all influence the adoption intention and decision-making processes of supply chain participants.

2.6. Counterfeits prediction

Counterfeits act as a barrier to innovation, hinder investment in research and development and weaken intellectual property laws. The most recent study (Amankwah-Amoah, 2022) emphasizes health-related implications, such as a wrong feeling of protection against a harmful virus and a possible loss of faith in trustworthy treatments. Although counterfeit COVID-19 vaccines are on the rise, they revealed only replication and acceleration of a worldwide trend. In practice, government expenditures in robust border enforcement and technical expert training to monitor and inspect items to detect and eliminate defective ones are needed.

2.7. Immutability

Prior research (Baharmand et al., 2021, Biswas and Gupta, 2019) has reported on the negative aspects of blockchain technology, including its immutability. The immutability of blockchain technology, which prohibits the change of recorded data, may sometimes pose problems. For instance, if wrong or fraudulent data is placed into a blockchain, it cannot be edited or amended, which may result in inaccurate or untrustworthy data. When integrating blockchain technology in a variety of sectors, including healthcare and pharmaceutical supply chains, it is crucial to evaluate its possible downsides and limits, as shown by these studies.

3. Model description

This research aims to create a tracking system for distributing the COVID-19 vaccine across countries. The proposed traceability system enables tracking each manufacturing process step, from raw materials to patient delivery. Most vaccines are manufactured in the country where they are distributed; however, some are imported. They are all collected and sent to the main distribution centers. The vaccines are then disseminated regionally in urban and rural locations. The vaccines are subsequently available nationwide via hospitals, clinics, Pfizer hubs, and pharmacies. The proposed methodology for Vacledger system is shown in a flowchart (Fig. 2). For a comprehensive understanding of the proposed study, the association between the figures have been shown in Table 1.

Fig. 2.

Proposed methodology for Vacledger system using a flow chart.

Table 1.

The link between the figures.

Figure number	Figure caption (Description)
1	Outline of our study.
2	Proposed methodology for Vacledger system using a flow chart.
3	Proposed COVID-19 vaccine traceable supply chain network.
4	Framework for vaccine traceability system (stakeholders, blockchains such as Hyperledger Fabric, and decentralized storage system).
5	Hyperledger Fabric enables a peer to connect with product demands and digital authority through APIs and protocols for secure communication and data sharing, validating authenticity using the consensus method before adding to the distributed ledger.
6	Hyperledger Fabric transaction flow diagram — Step 1: Requesting transaction by user-node; Step 2: A User-node sends a transaction proposal to the approver peer nodes; Step 3: Approver checks the transaction and generates approval signatures; Step 4: User-node collects signatures confirmation; Step 5: User-node sends the signatures to the product request; Step 6: Product request and digital authority verify signatures; Step 7: Update the peer nodes’ ledgers by broadcasting a message to peers.
7	Smart contract for regulatory compliance and border authorization facilitates collaboration between vaccine import and export countries.
8	Vaccine Registration Smart Contract: facilitates the collaboration between consolidation, the vaccine ingredients provider, manufacturer, the external company (vaccine importing company), and approver.
9	Smart contract for stock accumulation enables collaboration for the stocking up of vaccines among consolidation, vaccine ingredient provider, importing company, and approver.
10	Smart contract for location tracing update enables collaboration among consolidation, vaccine ingredients provider, importing company, approver, and new vaccine registers with distribution and phase updates.
11	Smart contract tracking model demonstrates the deployment of four smart contracts (registering, transferring, tracing, and monitoring) in the blockchain.
12	Operation of proposed smart contracts (VRSC, SASC, TUSC, RCBASC) on the Vacledger system is detailed in Table 4.
13	Vaccine distribution process in sequence diagram: This procedure is conducted between the manufacturer, external company, and distributor. Once an agreement has been reached, the manufacturer and the external company update the smart contract (LTUSC) with shipment-related information, which is then shared with all parties. When all vaccines have been received, the stock is updated. The distribution procedure will then begin. From the main distribution, vaccines are sent to the zone distribution, hospitals, and phases. Hospitals may seek additional vaccines, whereas manufacturers may seek confirmation. The hospital may communicate with the manufacturer immediately after delivery. When constructing blocks, transactions had to be validated. The transaction is valid if the value can be identified and its address returned to the stakeholder. A verified block is generated and registered appropriately if the transaction is new.

The production, manufacturing, and distribution procedures have grown drastically throughout the years. Traceable vaccines using blockchain-enabled technology may be used to help build an immutable vaccination traceability system that demands source information, vendor data, vaccine packaging, and vaccine stock information. Using blockchain for COVID-19 vaccine supply chain traceability and counterfeit detection may boost vaccination process effectiveness, efficiency, and trust in the vaccines’ authenticity and safety. As shown in Table 2, the parties involved in the COVID-19 vaccines supply chain are traceability listed.

Table 2.

Vaccine supply chain stakeholders.

Stakeholder	Description
Consolidation	The government oversees all consolidation. It complies with all permission and authentication requirements. The government must establish rules and regulations and provide border authorization for new agreements about vaccine importation tariffs if new vaccines or new suppliers exist.
External company	All nations cannot produce COVID-19 vaccines. Some nations must import them from where they are produced. As a result, when the vaccines are imported, they are recorded in the Vacledger and delivered in accordance with the agreement, which has been signed by both the import company and the government.
Ingredient provider	A supplier provides the producer with raw goods and some other active components. Identifiers for those raw goods are stored in the Vacledger, such as name, identification code, the amount provided, and date delivered so that interested parties can determine the source of such raw resources in the case of a return.
Manufacturer	The manufacturer’s most important job is to produce the vaccines and then ship them out. They also must keep all the vaccine information up to date to safeguard all standards. They must provide information about the manufacture of the vaccine and obtain authorization for the process. Once the vaccine has been manufactured, the manufacturer may then record its data.
Main distribution center	This facility has both locally manufactured and imported vaccines. The vaccine ledger is updated with the most recent information on vaccine amounts and categorization. Hospitals in rural, urban, and regional areas get those supplies.
Zone distributor (Remote, Metropolitan, and Regional Areas)	Many countries split the distribution into rural, metropolitan, and regional areas to help ensure the speed and equality of the distribution. Vaccines used to combat the outbreak come from the main distributor. As part of its duty, this secondary distributor distributes vaccines to hospitals. Every transaction is added to the vaccine ledger in the vaccine registry.
Hospitals, Pfizer Hubs, Clinics	A hospital may establish a direct transactional connection with end-users (patients). The vaccines are delivered to the hospital by government delivery organizations, and the vaccination is done by hospitals with access to the patient’s health information.
Phase I/II/III (Patient)	An approved patient can see, trace, and monitor information about any vaccination from the Vacledger (VApp). Patients may also be involved in the pharmaceutical supply chain system because they order their prescriptions from the pharmacy themselves. The patient may play the role of a casual actor, and they can inquire and ask the questions they want to link to vaccine stores in the Vacledger. Patients must register and enroll themselves to be included in the approved list of collaborating stakeholders before they can access and query the Vacledger data.

Vaccine production, manufacturing, and distribution procedures have grown significantly through the years. Using blockchain-enabled technology, traceable vaccines may be used to help build an immutable vaccine traceability system that demands source information, vendor data, vaccine packaging, and vaccine stock information. It is the process of locating the origin and legitimacy of vaccines by allowing the parties involved in the vaccine supply chain (government, vaccine ingredients provider, manufacturers, external company, zones, distributors, pharmacies, and phases) to track and trace the flow of executed transactions between them that is known as “vaccine traceability”. Fig. 3 illustrates the COVID-19 vaccine traceable supply chain network.

Fig. 3.

Proposed COVID-19 vaccine traceable supply chain network.

3.1. Blockchain technology for traceability

Traditionally, centralized methods have been used to help track pharmaceutical supply chains. A blockchain-based system provides security, transparency, immutability, traceability, and authenticated transaction histories. That system can be used in various corporate contexts, such as a distributed, unchangeable, shared ledger (Gamal, Abdel-Basset, & Chakrabortty, 2022).

The private-permissioned blockchain, for example, the Hyperledger Fabric platform (Hyperledger, 2018) has been chosen as our solution. Anyone joins a public blockchain and participates in the network’s essential functions. Only chosen entries of verified participants are allowed on a private blockchain, and the operator has the authority to overrule, alter, or remove the required entries. Our study uses a private-permissioned blockchain for the proposed Vacledger traceability system. Thus,

• (i)Only authorized participants can access the data in the Vacledger system;
• (ii)Managed by a group of nodes pre-define in the Vacledger system; and
• (iii)Only a few nodes are responsible for data management. It contributes to the acceleration of decision-making while maintaining scalability in the Vacledger system.

This private-permissioned blockchain network enables access to raw data using common standards, which aids in detecting counterfeit vaccines and provides information for initiating medication recalls. Due to these advantages, standardization and regulatory harmony across different nations and vaccine regulating agencies may be achieved using shared data interchange. The private-permissioned blockchain is a suitable platform for businesses that require numerous networks between many organizational divisions. Such private blockchains are limited to only known stakeholders with verified IDs. These private blockchains concentrate on specific supply chain weaknesses and data to address patient privacy difficulties and problems inside the vaccine supply chain. By bridging the gap between today’s technologies and historical systems, blockchains help provide scalable, auditable provenance for vaccine tracking data.

3.2. Blockchain-enabled smart contracts

In healthcare, smart contracts are now being used to address concerns such as electronic medical records, accessibility, sharing, and storage of sensitive data, medication tracking, and access restrictions. Smart contracts are a vital element of pharmacy supply chain electronic signature authorization (Sylim, Liu, Marcelo, & Fontelo, 2018). Operational and technical expenses are reduced by replacing third-party solution providers for numerous transactions. Hash functions generated in a tree-like design are used in smart contracts to protect and expedite data testing using Merkle trees (Agrawal et al., 2021). Each address is identified as an account with a certain amount, and transactions maintain information on capital transfers across accounts. When the value of the asset being transferred equals or is greater than what is required in the transaction, a transaction is completed and stored in the blockchain. The unspent transaction output model does not include the concept of an account tied to an ID or location (Chakravarty et al., 2020). It deals only with transacting and spending assets, which are outputs from prior transactions (assets).

4. Proposed Vacledger: Vaccine traceability structure

Building our private-permissioned blockchain network with different untrustworthy partners and their assets allows us to create a unique supply chain for our vaccines that avoids trust issues. When dealing with participants and stakeholders, the most crucial factor is service providers’ confidentiality, security, and privacy. Hyperledger Fabric incorporates a uniqueness and access management system that validates the identities of all individuals on the system and maintains the role of a given User ID. It includes a membership service called Medledger, that sets norms and regulations among various pharma supply chain players to maintain confidentiality, transparency, and security (see Table 3).

Table 3.

Abbreviations and acronyms used for Vacledger.

Acronym	Description
APT-SC	Automotive Industry Smart Contracts
Agri	Agriculture
ASC	Agriculture Supply Chains
BT	Block Technology
DA	Digital Authority
DEMATEL	Decision-Making Trial and Evaluation Laboratory
EPC	Electronic Product Code
ERC	Non-fungible Token
GPS	Global Positioning System
IPFS	Inter Planetary File System
ISM	Interpretive Structural Modelling
ISS	Information System Successful Model
LMC	License Manager Chain Code
LTUSC	Transaction Update Smart Contract
MSC	Managed Supply Chain
MSP	Managed Supply Procurement
NDVP	National Arrangement and Inoculation Arrange
PoA	Proof of Authority
Pr	Product Request
RCBASC	Regulatory Compliance and Border Authorization Smart Contract
RFID	Radio Frequency Identification
RW	Readset and Writeset
SASC	Stock Accumulation Smart Contract
SC	Supply Chain
SDM	System Dynamics Model
TPB	Theory of Planned Behavior Model
Tx	Transaction
UXTO	Unspent Transaction Output
VRIC	Vaccine Register Chain Code
VRMC	Vaccine Registration Manager Chain Code
VRSC	Vaccine Registration Smart Contract
WSN	Wireless Sensor Network

A new innovative model for non-determinism, resource depletion, and performance attacks enhances the patient records monitoring systems of participants involved in the system (Mattke, Hund, Maier, & Weitzel, 2019). Explain in detail how the Hyperledger Fabric method works in the vaccine supply chain, using the example of a real-world chain. A supply chain comprises many stakeholders, whether they are registered or not. The first stage is that this system registers vaccine-related stakeholders, building trust among them and making it possible to administer their personal information. The transmission of their data to the blockchain will then be straightforward, and everyone’s privacy may be enhanced.

This section details how smart contracts work in a vaccine supply chain, using the example of a real-world chain. A supply chain comprises many stakeholders, both registered and unregistered. In the first stage, the system registers vaccine-related stakeholders, thereby building trust and enabling them to administer their personal information. It is then a straightforward process to send their data to the blockchain. Three concepts should be verified in the private-permissioned blockchain method (for example, Hyperledger Fabric).

4.0.1. Digital authority

The ability to establish a private blockchain network to author many untrustworthy parties in the vaccine supply chain allows us to improve its overall security. A specific core license is issued to each engaged participant that links that individual’s peers and orders to the organization. Each stakeholder is assigned a unique digital authority (DA) certificate to simulate a network where participants may utilize their digital authorities. In Hyperledger Fabric, transactions and interactions are signed using a stakeholder’s private key (a Keystore), after which they are validated with a public key (a signature store). As a result, a DA handles certificate issues, including renewal and revocation of various kinds of certificates granted to end-users and organizations.

4.0.2. Peer

A peer performs two roles: an approver and a committee member. When a transaction proposal is received, the approver evaluates considering the approver policies in place or creates new policies as required. The peer also keeps vaccine ledger inquiries up-to-date.

4.0.3. Product request

The product request results in blocks in which transaction proposals that have received the approval of the peer nodes on the blockchain platform are presented. Any approval transaction requires the signature of each peer. These blocks are subsequently transmitted to the peers of the blockchain platform for validation. The consensus procedure consists of three steps. First, transactions are submitted. Second, they are ordered. Third, bundles of events are produced into blocks. Then, the verified and committed blocks are recorded in the ledger. A three-step process is achieved by using Kafka, Raft, and Solo ordering service nodes.

A minimum consensus requirement must be met to join the blockchain; in our case, the Hyperledger Fabric network. The Hyperledger Fabric uses the Byzantine fault tolerance consensus mechanism to have transactions ordered and executed. Because it processes over 3500 transactions per second, Hyperledger Fabric is significantly more efficient than other Keystorelockchains (Yusuf, Surjandari, & Rus, 2019). Hyperledger Fabric differs from previous distributed ledger systems in several distinct ways, some of which are:

• (i)Hyperledger Fabric allows users to execute a wide range of transactions on a private permissioned, and flexible platform on a P2P blockchain network.
• (ii)Approval in the achievement of agreement among network stakeholders is aided by the pluggable approval model, which is flexible and modular.
• (iii)Using network transactions that guarantee privacy and integrity is part of the process. It enables member organizations to link and communicate beyond organizational boundaries, allowing them to achieve privacy and secrecy.
• (iv)The smart contracts for governance and versions offered are suitable.
• (v)Transaction execution on other blockchains has lower latency than competing systems.
• (vi)These operations include continuous upgrades and asymmetric variant support, all of which keep the company running.
• (vii)Keyed queries, range queries, and synonym queries are all supported.

Fig. 4 shows how the private-permissioned blockchain method works with traceability in it. It works by reversing the traceability of the ingredient providers, manufacturers, and distributors. All the locations and products can be traced using Vacledger. Traceability happens when all supply chain transactions and associated data are accessible to patients. This approach is achieved by constructing an Hyperledger Fabric approach in which business logic is expressed using a smart contract, and all network nodes agree upon the outcome. As shown in Fig. 4, the Hyperledger Fabric deployment concept demonstrates how participating parties are interconnected, and channels are built to ease transaction flows across different stakeholders.

Fig. 4.

Framework for vaccine traceability system (stakeholders, blockchains such as Hyperledger Fabric, and decentralized storage system).

4.1. Establishment of the private-permissioned blockchain model

The “trace backward” criterion is used in our vaccine traceability system. These practical standards are classified as “trace back”: the chain of transactions starts with the ingredient provider, includes the manufacturer, and follows the supply route to the product’s endpoint. In the “track forwarding” phase, the current location of the vaccine in the supply chain is monitored data in the current transaction flow (patient) is associated with it. In the case of traceability of controlled substances, the technology is deployed with the help of an Hyperledger Fabric network in which smart contracts are used to execute business logic, and all nodes on the network establish the results. The implementation approach shown in Fig. 5 is a case study of how participants may implement an application’s business logic.

Fig. 5.

Hyperledger Fabric enables a peer to connect with product demands and digital authority through APIs and protocols for secure communication and data sharing, validating authenticity using the consensus method before adding to the distributed ledger.

When several stakeholders draft a transaction proposal and distribute it to a peer, the first attempt is to determine whether this transaction is recorded in the validated ledger. If the proposal is successful, it sends an approver confirmation to verify it. Peers investigate to see whether the transaction is legitimate as well. In conclusion, the approver follows up and sends this information to the product request for verification. Once validated, the transaction is redistributed across peers. Stakeholders are connected, and a transaction flow is created to connect them. The Vacledger network’s design must consider its cyber–physical properties and features.

Our vaccine traceability scenario comprises two distinct and asynchronous transaction processes. Vaccine transactions are classified as either vaccine transportation or supply chain data transmission. In Fig. 6, smart contracts are used to implement and monitor the transaction flow among stakeholders. Due to this process feature, all participants can see all transaction papers at any moment. Various parties autonomously initiate, construct, and deploy smart contracts on a blockchain platform with private-permissioned to monitor and track the authenticity and transparency of each vaccine in the supply chain. In Vacledger, those smart contracts are used to register medicines, ingredients, and delivery and monitoring data. They ensure that these records are immutable, transparent, and time-stamped. Four separate smart contracts are used for our traceability system: RCBASC, VRSC, SASC, and LTUSC.

Fig. 6.

Hyperledger Fabric transaction flow diagram — Step 1: Requesting transaction by user-node; Step 2: A User-node sends a transaction proposal to the approver peer nodes; Step 3: Approver checks the transaction and generates approval signatures; Step 4: User-node collects signatures confirmation; Step 5: User-node sends the signatures to the product request; Step 6: Product request and digital authority verify signatures; Step 7: Update the peer nodes’ ledgers by broadcasting a message to peers.

4.1.1. Regulatory Compliance and Border Authorization Smart Contracts (RCBASC)

RCBASC is deployed automatically when new vaccines from third parties are imported (Fig. 7). The contract document serves as a storage facility for various parties’ rules and regulations on vaccine order requests. The contract is prepared by creating and executing the addCompliance() function, which is a utility function that collects rules and regulations-related information from the contract. The contracts store data such as taxes paid by various countries and vaccine-buying countries.

Fig. 7.

Smart contract for regulatory compliance and border authorization facilitates collaboration between vaccine import and export countries.

Managing the supply chain and adhering to regulatory requirements are intertwined when vaccines cross-national or state borders. It also checks whether vaccine stock can cross country borders by using the passBorders() method and creating and executing. After successful deployment, the orders for vaccines are added to the VRSC.

4.1.2. Vaccine Registration Smart Contract (VRSC)

A VRSC program is established and executed to register imported, manufactured, and active vaccine components. This is performed to record vaccines; the VRSC contains data for these vaccines. Additionally, the contract includes all the necessary information on the recipient, such as the sender’s address, vaccine code, vaccine name and ingredients, and current time stamp. Stock accumulation Smart Contract 1 (SASC1) starts in addition to the VRSC once a vaccine is registered. Export companies, manufacturers, and VRSCs collaborate to develop the product (Fig. 8).

Fig. 8.

Vaccine registration smart contract: facilitates the collaboration between consolidation, the vaccine ingredients provider, manufacturer, the external company (vaccine importing company), and approver.

4.1.3. Stock Accumulation Smart Contract (SASC)

Once a new vaccine is included in the VRSC, a SASC is installed automatically. The contract stores medication, production, and registration information for all manufacturers and external companies’ vaccines. The addstock() method is constructed and executed to obtain the required stock information for the contract. The SASC transmits its contract address to the VRSC so both have the latest contract information (Fig. 9).

Fig. 9.

Smart contract for stock accumulation enables collaboration for the stocking up of vaccines among consolidation, vaccine ingredient provider, importing company, and approver.

4.1.4. Location Tracing Update Smart Contract (LTUSC)

When additional stock-related data are introduced to the SASC, the LTUSC is immediately implemented. That material is sent to all stakeholders to ensure that everyone has up-to-date information on the new transactions attached to the contracts for the VRSC and the SASC. The transaction history upgrade is implemented using the new method updateTr(). Once the LTUSC is deployed, it informs the SASC of its contract address. Through the LTUSC, users’ transactions and information, such as the transaction hash, sender and recipient addresses, and time stamps, are saved. It is critical to provide details on a vaccine, including the vaccine and its related component information (Fig. 10).

Fig. 10.

Smart contract for location tracing update enables collaboration among consolidation, vaccine ingredients provider, importing company, approver, and new vaccine registers with distribution and phase updates.

Fig. 11 shows how smart contracts keep track of functioning in the blockchain and shows all four smart contracts being deployed. The contract specifics are fully presented, showing how smart contracts function.

Fig. 11.

Smart contract tracking model demonstrates the deployment of four smart contracts (registering, transferring, tracing, and monitoring) in the blockchain.

4.2. Implementation of Vacledger vaccine traceability system

The proposed private-permissioned blockchain-based vaccine traceability system provides a complete and irreversible system that enables all stakeholders to access accurate and relevant information without needing a central authority. Stakeholders may inquire about a vaccine’s transfer history, source, or origin via the VApp. Only transaction data are stored or edited on the Vacledger. Finally, any valid transactions are tracked in Vacledger, and their associated funds are updated and uploaded to the system.

This section details how the proposed blockchain-based medication traceability system was implemented using the execute-order-validate structure in the private-permissioned blockchain. Transaction-related actions are captured and recorded by the developed framework. Vacledger is coupled with a decentralized storage system that provides optimum visibility and storage capacity to store many medications and responds to real-time changes in the supply chain. Vaccine regulatory authorities first onboard and register all involved parties in the vaccine supply chain system on a peer-to-peer private-permissioned blockchain. Partners (stakeholders) are registered by the regulatory body that maintains and regulates the blockchain system by using a registration mechanism inside the smart contract. A private blockchain network is created. The network is accessible only to those stakeholders who are granted access to it.

All stakeholders have additional security by linking to the registration using a virtual private network. Upon registering, patients give simple information such as their name, social security number, address, and telephone number. They will be part of the organization’s body that carries out drug regulation, as shown in Fig. 4. The vaccine regulatory body checks the records and issues a smart contract location to confirm the information in the files. All parties have finished the enrollment process, and the operations may now be achieved on the network. This eliminates any possibility of tampering with data saved on the Vacledger. Imported and locally manufactured vaccines are registered using the register() method.

A medication transaction (an activity involving the use of a smart contract) is sent to the blockchain Vacledger, which is then deemed accepted. The vaccine registration proposal has characteristics, including the vaccine ID, name, ingredients, importing quantity, and expiration date. The transaction proposal is then confirmed and verified by the blockchain network’s accessible and registered peer nodes using the enrollment and approval policies. Approvers are called “peers”.

The vaccine registration process is simulated and executed by numbered approval partners indicated in the approval policy. When the process is complete, the peer encodes and digitally signs their work and the work of all the other approved peers, and the final work is referred to as approval. That permission includes read and write values and extra metadata such as transaction information. The approval is returned to the stakeholder as a proposal to proceed with the transaction. It is important to note that the sale will not go through until the import vaccine/manufacturer node has received all the necessary clearances. Once the transaction has been confirmed and authenticated, it is sent to the product request. The promotion stage of the proposal process is known as the approval phase.

Following the proposal approval phase, the manufacturing node assembles all the approvals and declarations into the product request on the blockchain network. A transaction response includes the transaction context, transaction information, and approvals. The product request uses programmable consensus protocols per channel to determine and set the correct sequence of all provided transactions. Multiple identical vaccine-related transactions are linked in blocks (a hash-linked sequence of blocks). Those blocks (or a linked series of blocks) are assigned to individual transactions based on the product request. Declaration protocols are improved by breaking down the stock procedure into portions.

The deployment phase is often referred to as the “working phase”. When the product request obtains all transactions and all state requirements, it combines them and distributes them. Fig. 6 shows the packets’ declarations to peers inside the network. Fig. 11 shows that vaccine registration, transferring, tracing, and monitoring in the vaccine supply are simplified by this system. Deploying the VRSC contract to the Hyperledger Fabric network and publicizing its contract address, which the system manager does. Fig. 12 shows that the procurement process is executed between:

Fig. 12.

Operation of proposed smart contracts (VRSC, SASC, TUSC, RCBASC) on the Vacledger system is detailed in Table 4.

• (i)a vaccine was imported by the government and exported to a private enterprise;
• (ii)the provider and manufacturer of vaccination ingredients.

Agreements must be reached before the procurement process may proceed. Once a decision has been made, the procurement procedure starts. Once VRSC (smart contract) is in place, it is possible to begin registering imported vaccines, manufactured vaccines, and their specific ingredients. Autonomous deployment of the SASC (smart contract) for every vaccine registered via the VRSC (smart contract) occurs at the moment of vaccine registration. The LTUSC smart contract is implemented independently of the SASC (smart contract) simultaneously. Smart contracts are triggered in response to the SASC (smart contract) being deployed. The supply chain’s LTUSC will be used to update transaction data when vaccines are transported from one party to another, as shown below:

• (i)the vaccine ingredients provider supplies the ingredients to the manufacturer
• (ii)the distribution center receives both manufactured and imported vaccines
• (iii)the distribution center supplies vaccines to Zone distribution
• (iv)zone distribution supplies the vaccines to hospitals
• (v)the hospital supplies the vaccines in Phases.

An immutable trail of all vaccine and ingredient transactions is maintained by the LTUSC contract, which can be accessed and confirmed at any moment by utilizing our proposed traceability solution for vaccines. Functions such as deploying smart contracts, procuring vaccine ingredients, registering imported vaccines, distributing, making wholesale purchases, and sourcing vaccines are described in Sections 4 through 6.

4.3. Deployment of smart contracts

When two countries agree to accept the rules and regulations for importing vaccines from another country, the RCBASC is started by the compliance() function. Then passBorders() function is used to transport vaccines across national and state borders. A VRSC is initiated and deployed to the private-permissioned blockchain network, and its contract address is created. When the VRSC is up and running, registering all of the vaccines and their various components can begin for both the imported and locally produced versions. All vaccines registered via the VRSC are autonomously deployed when registered on the SASC. All SASCs have their LTUSCs active simultaneously, independently of each other. Once the SASC is deployed, the registration and addition of the stocks to the database are triggered by the register() and addstock() functions. When vaccines are transported among stakeholders, updateTr() along the supply chain updates their transaction details. All vaccines, vaccine components, and their corresponding transactions are tracked on a fixed Vacledger (the LTUSC). This information can be compared and confirmed whenever required via the traceability system.

Table 4.

Transactions occurring in the vaccine traceability system.

Step	Description
1	External company establishes terms and conditions of vaccine supply with respective country consolidation
2	External company gets the approval of vaccine supply from the respective country consolidation
3	Vaccine registration smart contract (VRSC1) deployed by the external company (supplier vaccine)
4	External company register the imported vaccine in the VRSC1
5	New stock accumulation smart contracts (SASC1s) deployed
6	SASC1 return its SASC1 address to VRSC1
7	Imported vaccine registration acknowledged back to the external company
8	Stock of vaccine added to the SASC1 depending on the type and other information related to vaccine registered and stored in the VRSC1
9	New location tracing update contract (LTUSC11) deployed
10	LTUSC11 return its LTUSC11 address to SASC1
11	External company adds the stock information related to the vaccine in the SASC1
12	Once imported vaccinations have been added to and updated in the contracts of participating organizations, they are sent to the main distribution center
13	External company then updates the imported vaccines transaction information in the LTUSC11
14	Vaccine registration smart contract (VRSC2) deployed by the manufacturer
15	Ingredient provider registers the vaccine ingredients in the VRSC2
16	New stock accumulation smart contracts (SASC2) deployed
17	SASC2 returns its SASC2 address to VRSC2
18	Ingredients of registered vaccine acknowledged back to the ingredients provider
19	Stock of vaccines added to the SASC2 depending on the type and other data associated with vaccines registered and held under the VRSC2 contract
20	New location tracing update smart contract (LTUSC21) deployed
21	LTUSC21 returns its LTUSC21 address to SASC2
22	Ingredients provider adds the stock information related to the ingredients of vaccine in the SASC2
23	Vaccines are transferred to the manufacturer once the vaccine ingredients are added and updated in the respective contracts related to participating entities
24	Ingredients provider updates the active ingredients transaction information in the LTUSC21
25	Manufacturer registers the vaccines in the VRSC2 contract
26	New stock accumulation contract (SASC2) deployed for vaccines
27	SASC3 returns its SASC3 address to VRSC2
28	Vaccines registered (vaccine acknowledged back to the supplier that has been registered)
29	Stock of vaccine-related data added to the SASC3 based on the type and other vaccine-related data stored in the VRSC2
30	New location tracing update smart contract (LTUSC31) deployed
31	LTUSC31 returns its LTUSC31 address to SASC2
32	Vaccine stock-related information updates with the manufacturer from SASC3
33	Registered vaccines passed to the main distribution center from the manufacturer
34	Information on registered vaccine passed from manufacture to distributor, then passed to LTUSC31
35	Main distribution passes the vaccines to zone distributors
36	Main distribution then updates the information of registered vaccines passed from main distribution to zone distributors, then passes it to LTUSC31
37	Zone distributors pass the vaccines to hospitals
38	Zone distributors then update the information of registered vaccines passed from zone distributors to hospitals, then passes it to LTUSC31
39	Hospitals pass that information to phases
40	LTUSC31 contract enables phases to simplytrack and trace the needed vaccination information from the system
41	Using the LTUSC31 contract, Consolidation (government) can track and trace specific vaccine information from the Vacledger system.
42	Consolidation monitors all activities pertaining to the COVID-19 vaccine supply chain

4.3.1. Regulatory compliance and border authorization for purchasing vaccines

This smart contract includes agreements with other countries for procuring vaccines. Imported vaccines, the number of vaccines, and taxes paid (included) apply to those countries. First, the agreement of the importing country should be checked to see whether it is included in this smart contract and whether there are any changes in the contracts automatically. If there are no changes in the agreement, vaccines are purchased and can be sent to register() vaccine to VRSC1. If no agreement exists, new rules may be added by addCompliance(). If there is a mismatch between the rules and regulations, it shows as an error according to Algorithm 1. When vaccines traverse national, or state boundaries, supply chain management, and regulatory compliance are linked. By using the passBorders() function and making an execution, it determines whether vaccination stock may cross national borders. The RCBASC contract also considers border regulations when rules and regulations are considered. If there are no changes in the border authorization, this may help the LTUSC contract to cross the different types of borders smoothly. If no authorization exists, new rules may be added by addCompliance(). If there is a mismatch between the authorizations, it shows as an error.

4.3.2. Purchasing imported vaccines

The procurement phase is initiated when the external company and the governance institution reach a consensus. Once the governance institution has received a response confirming receipt from the external company, the institution updates the smart contract using the LTUSC11’supdateTx() function, as shown in Fig. 8. Those functions include the following procedures:

• (i)The governance institution calls the purchaseVaccine() function to start purchase orders. That function contains the external company and country governance addresses, the count code, and the governance institution’s private key used to check the request’s validity, identification, and integrity.
• (ii)The external company executes a feedbackVaccine() function if the governance institution’s request is legitimate.
• (iii)At this point, the vaccine components have been delivered; thus the external company sends the imported vaccine to the government institution and invokes sendVaccine() to verify that.
• (iv)When the active substances are delivered, the government institution uses the receivedVaccine() function. Those data are stored in LTUSC11 once the procurement procedure has finished, as shown in Table 4.

4.3.3. Purchasing ingredients for manufacturing

The procurement phase is initiated when the ingredients provider and manufacturer reach a consensus. Once both parties agree, the procurement process is launched, the manufacturer inquiries about the raw materials they need, and the ingredients provider confirms that they have the active components. Once the ingredients provider has received the response confirming receipt of the ingredients, the ingredients provider updates the smart contract using the LTUSC21’s updateTx() function, as shown in Fig. 13. Those functions include the following procedures:

Fig. 13.

Vaccine distribution process in sequence diagram: This procedure is conducted between the manufacturer, external company, and distributor. Once an agreement has been reached, the manufacturer and the external company update the smart contract (LTUSC) with shipment-related information, which is then shared with all parties. When all vaccines have been received, the stock is updated. The distribution procedure will then begin. From the main distribution, vaccines are sent to the zone distribution, hospitals, and phases. Hospitals may seek additional vaccines, whereas manufacturers may seek confirmation. The hospital may communicate with the manufacturer immediately after delivery. When constructing blocks, transactions had to be validated. The transaction is valid if the value can be identified and its address returned to the stakeholder. A verified block is generated and registered appropriately if the transaction is new.

• (i)The manufacturer calls the purchaseEvent() function to start purchase orders. That function contains the manufacturer and ingredients-provider addresses, the ingredients code, and the manufacturer’s private key used to check the validity, identification, and integrity of the request.
• (ii)If the manufacturer’s request is legitimate, the ingredients provider executes a feedbackEvent() function.
• (iii)At this point, the active vaccine components have been delivered; thus the provider sends the active vaccine ingredients to the manufacturer and invokes sendEvent() to verify that.
• (iv)When the active substances are delivered, the manufacturer uses the receivedEvent() function. Those data are then stored in LTUSC21 once the procurement procedure has finished, as shown in Table 4.

4.3.4. Registration of vaccine ingredients

Active vaccine components are the first stage in the medication manufacturing process. Registration is completed after the active vaccine components have been acquired. This contains data on the registration and labeling of active ingredients and a list of the items consigned for a specific medication. Vaccine and ingredient names, codes, and other relevant information must be unique.

• (i)The ingredients provider uses the register() function in the VSRC2s to register the vaccine ingredient information, which independently installs the SASC2.
• (ii)The provider gets the registration result.
• (iii)Once the ingredients in the stock have been verified, the provider must next register those ingredients and add them to the contract’s blockchain by calling the addStock() function in the SASC2. That requires more work before the LTUSC21 is implemented; however, its contract address is also registered in the stock ingredient information. Fig. 12 shows that the final execution result is delivered to the provider.

4.3.5. Vaccine registration

The vaccine producer (manufacturer) and government institutions are responsible for the entire process of vaccine registration, which includes the handling of all information about the medication, including the method of shipment, placement of SASC1s, SASC3s, LTUSC11s, and LTUSC31s, and the start and end of the contracts. In implementing the Vacledger system, the pseudocode (algorithms) used throughout the vaccine supply chain is defined in the implementation phase. VRSC1 is used by a provider, a manufacturer, as mentioned in Section 4, an external company, and a government institution. That code is performed by invoking the register() function, as seen in Algorithm 2. The VRSC information is registered using that form to note the medicines and their respective data, such as vaccine codes, vaccine names, active vaccine components, and time stamps. The VRSC can also record all the mapping information that was included in the SASC, such as the medication code and its associated stock information. Fig. 5 illustrates the input variables for the register() function, accepts a sender address, vaccine code, vaccine name, active ingredients, and current time stamp.

For clarity, a diagram is included in Fig. 5 showing the vaccine registration process with the Vaccine Registration Initializer chain code serving as the primary chain code for that procedure. That smart contract is responsible for the development, execution, verification, and approval of the proposal received by the manufacturer shown in Fig. 5. Vacledger’s smart contract is helpful to producers because it allows them to prepare, upload, and share vaccine registration data. Also, the smart contract verifies whether the associated medication is registered (i.e., legally in existence). If the function takes a YES response, it reverses an exception message. Nevertheless, the register() function adds the medication and other relevant information to the VRSC, even if the user is not registered. After executing Algorithm 3, it passes the corresponding SASC address to the VRSC, where the vaccine-related information is verified to have been updated.

The vaccine supply chain uses the License Manager Chain code to gather and store data on all active vaccine ingredient components and imported vaccines, which is then shared with the manufacturer and governance institution. Once the medication vaccine information has been registered by the manufacturer and governance institution, the smart contract shown in Fig. 5 is used to update the Vaccine Registration Initializer smart contract. When a new vaccine is recorded in the VRSC, the SASC is distributed autonomously. That procedure is visible to all participants within the supply network because the SASC captures vaccine stock-related information.

The deployment of the SASC is completed by creating and executing the addstock() function. That function accepts the following input values: the address of the sender, the stock number, the current time stamp, the previous address, the stock manager (SM), and the stock count. Suppose the stock number of that specific vaccine is recorded in the contract. In that case, the program calls a reversion function, which generates an error message indicating that the stock number has already been registered. If the stock number is not discovered, the function registers the stock number of vaccines with specific ingredients and imported vaccines and their respective inventory data in the chain code. The smart contract’s current value then increases. Upon returning the LTUSC address, the SASC provides regular updates so that the current information may be provided in the LTUSC.

4.3.6. Distribution of vaccines

This step is performed between the main distribution and the zones. Once both parties have agreed on a distribution plan, the main distribution uses the addTx() function, as shown in Algorithm 4, to create and fill in shipping-related information, which is then sent to all parties. The vaccine traceability procedure, which includes updating and running addTx() in the LTUSC, is implemented, as shown in Fig. 12. Using smart contracts, a vaccine registration administrator may obtain data on a manufacturer’s activities, and their vaccine-related activities, such as the time stamp shown in Fig. 12. All transactions related to the vaccine supply chain are tracked and updated by that function (from external company/manufacture to patient). To trace the location of medicine in the supply chain, the addTx() function is called. Each transaction comprises inputs that include senderAddress, previousTx, shipmentManagers, and txCount as inputs.

Algorithm 4 verifies whether a prior transaction relates to a particular vaccine and, if so, verifies whether the transaction is legitimate. If the transaction amount is legitimate, it returns the vaccine’s address to the shareholder. In contrast, if prior transaction data are not discovered in the contracts, or the contracts are not genuine, the medication is counterfeit. Once zone distributors and phases (stakeholders) have agreed on a standard solution, the zone distributors call the addTx() function, updating LTUSC31 along with the results. Vaccines purchased by patients are bought from clinics or hospitals, which means the patients are unaware. Therefore, there is no way to know who of our phases will buy the vaccines ahead of time.

4.4. International borders and shipments

Cross-border shipping is the movement of products across borders Table 5. The products may be subject to import charges depending on trade agreements and de minimis values. Importation and distribution of COVID-19 vaccinations were handled through the supply chain. As a result, several concerns and obstacles arise.

Table 5.

International borders and shipments issues and challenges.

Challenge	Description
Uncertainty about the lead time	Shipment lead times and their variation is determined by the coordination of logistical operations between supply chain participants as well as infrastructures that are either lacking or underutilized. This is particularly true for cross-border shipments. Importing authorities need specific certifications for some items (such as immunizations). In addition, government officials are constantly attempting to create changes and certificate validations, creating new obstacles.
Non-guaranteed travel time	Transit time varies depending on the point of origin and destination. Other factors contributing to non-guaranteed traveltime, including port delays, customs clearance delays, airline traffic jams, human mistakes, technological faults, weather conditions, and ship malfunctions, among others. Consequently, courier companies must preparefor the best and worst-case situations far in advance of their operations. If cargo transit times are delayed due to unanticipated circumstances, suppliers must be informed of the status, respond quickly, and have backup plans.
Border closures, access to territory returns	In certain nations, borders between provinces and states have been blocked due to the lockdowns. Transport delays for pharmaceutical raw materials and other necessities, as well as completed goods on their route to ports, have risen as aconsequently. Domestic transportation expenseshave increased due to a decrease in the availability of vehicles andlabor.
Transport and logistics problems	In several primary nations manufacturingCOVID-19 vaccines, only a few air freight carriers operate. Consequently, the cost of flying freight has tripled. Cargo transit through passenger aircraft accounts for a significant share of total air freight capacity. The cancellation of passenger flights has increased the need for cargo space.

5. Results & performance evaluation

This paper presents several key findings from an examination of blockchain technology adoption, which assisted in developing a modular method for tracking COVID-19 vaccines. Most of those vaccines are collected from local manufacturers or imported. Accordingly, the vaccine supply chain is building up. Many researchers identify the blockchain as an easy and secure tracking system. The private- permissioned blockchain technique enhances modular privacy in the proposed concept. Four smart contracts are introduced with algorithms that enable easy tracking of supply chain activity. Moreover, this paper discusses security, transparency, and performance scalability.

Table 6.

Comparison of different blockchain-based supply chain traceability studies.

Study	Related industry	Blockchain type	Zone wise distribution	Import and internal manufacturing	Compliance	Smart contract built for compliance	Traceability/Tracking data	Transparency	Performance scalability	Advantages of proposed system	Limitation of current approach
Kuhn et al. (2021)	Automotive	Public Ethereum	Not considered	Import materials and Internal manufacturing	Not considered and mention as future development	No	Name of the part, weight, packing date, part origin and cost, material name, material ID, assemble date, quality status, current status about process	Full data access to stakeholders	Tested using automotive industry smart contracts, gas used per function	Ensures system data safety, identifies the complex interaction between automotive partners, internal–external purchasing tracking	Data sovereignty, scalability limits, integrity of the stored data, lack of established regulations, possible DDoS and Sybil attacks, creating large numbers of pseudonymous nodes
Feng et al. (2020)	Agri-food	Public Blockchain	Not considered	Internal manufacturing	Not considered and discuss as limitation	No	Planting date, fertilizer amount per hectare, processing date, manufacturing date, location of the item, expiration date, current status (now), quality status of the food, seller ID	Considered under technical performance and traceability. Requirements: full information transparency	Discussed as system performance and technical performance	Ensures transparency and a secure food supply chain,identify key challenges in food traceability. Improved business processes and efficiency	Failures of interoperability: interoperability between ledger kinds (e.g., public and private). Communication problems: the capacity of IoT-based devices is significantly lower than the blockchain requires because nodes in the blockchain demand regular transmission and data exchange. Each ledger must be kept on its own node in the blockchain. Uncertainty in the regulatory environment and unlawful usage of the blockchain may occur.
Cao, Jia, and Manogaran (2020)	Steel products	Private Hyperledger Fabric	Country wise	Internal manufacturing and export	Discuss as rules and regulations( issue)	No	Manufacturer ID, manufacturer address, identity registration of members, product name, batch ID, source ID, delivery date, quantity, vendor ID, product user ID, product quality	Mentioned that only selected stakeholders can access the supply chain data	Data tampering success rate of the quality traceability system.Change in consumer satisfaction with the product, change of product information integrity, change in the number of product dispute cases.	Easily identifies the processing of steel products. Reduces the low transparency and incomplete data, tracks manufacturing safety	Lack of established regulations. Applying this model in different related fields might be difficult
Uddin (2021)	Drugs	Private Hyperledger Fabric	Not considered	Internal manufacturing -(India)	Not considered and discuss as limitation	No	Location of drugs,the current time stamp of consignment, drug name, drug ingredients, ingredient suppliers, consignment number, consignment count, transaction origin, receiver address, transaction count	Mentioned that only selected stakeholders can access the supply chain data	Considered and discussed under limitations of data standardization (storing irrelevant data on the ledger results in larger transaction sizes, which reduces efficiency and speed)	Identifies fake vaccines using the HF model. Using chain codes can monitor the performance of the stakeholders from manufacturing to delivering to the patient. Figures show all the operations of the supply chain running in the HF model.	Fear of sharing data due to data privacy issues of the stakeholders. Data scope: storing unimportant data creates additional large transaction sizes. Also, lack of established regulations, distributed storage, block ownership, and entries on the ledger. When ownerships change, various access permissions are required.
Agrawal et al. (2021)	Clothing	Private Hyperledger Fabric	Not considered	Internal manufacturing	Not considered and mention as future development	No	Origin of cotton, manufacturing HF name,the provenance of the product ID, organic cotton producer/supplier ID, yarn manufacturer ID, HF manufacturer ID, apparel manufacturer ID,the current status ofthe transaction, chemical ID, HF color ID	Mentioned that only selected stakeholders can access the supply chain data	Performance checking by an algorithm:the average time required to forecast target hash at various nonce difficulty levels	Identifies the complex interaction between clothing partners, tracks all transactions between stakeholders, ensures data safety	Develops organic cotton material block chain traceability as an example. If adopted for other material, this may change. Fear of data sharing due to data privacy of the stakeholders. Lack of established regulations. When nonce complexity and the number of transactions per block rise, there is a delay in block generation.
Qiu and Zhu (2021)	Vaccine quality control	Private & public Double-Chain Structured	Not considered	Internal manufacturing-china	Not considered	No	Vaccine name, vaccine batch number, vaccine specifications, date of production, quality guarantee period, production information records, examines temperature, intermediate process information records, examines humidity, exception information records,the hash of reviewer signatures, extra details and information	Mentioned that only selected stakeholders can access the supply chain data	Overall discussion of an increase in performance. Higheranti-counterfeiting performance.	Identifies the complex interaction between vaccine partners, ensures the data safety inthe system, ensures credibility in the system, easily monitors the behaviors of vaccinators, easy quality supervision	Focuses only on China. Lack of established regulationsand use of Ethereum means a high risk of malwareattacks, still inthe design stage; not in production yet, many stream requests were produced in a single instance, which might cause storage problems in Ethereum.
Baralla et al. (2021)	Agri food	Public Ethereum	Not considered	Internal manufacturing - Italy	Not considered and discuss as local rules affect for the business	No	Product name, packing date, manufacturing date, location of the item, expiring date, certifier ID, stock ID, stock amount	All stakeholders can be authorized as the system administrator. Full data access to stakeholders.	Estimation of transaction costs to create a production batch	Transactions easy with Ethereum, ensures data safety inthe system, identifies a proposed quality system, Ethereum public blockchain with permission editing for stakeholders, no need to buy a cloud solution or pay for service providers	Applying this model in different related fields might be difficult. Each company competitor can view data and verify all transactions within the ledger in a totally anonymous form, Limitations on the management of permissions by a central authority.
Mangla et al. (2021)	Agri food	Public blockchain	Not considered	Internal manufacturing-Turkey	Not considered	No	Farming ID, farming address, milk collecting date, processing date (milk bottles), inspection status, expiry date, storage, collecting center name, transaction status	Full data access to stakeholders	Not considered; it is a future development	Reduces food waste, increases good interaction between stakeholders, identifies food supply chain losses and animal health and welfare, proximity to food markets, food security, educating and promoting people toward healthy eating	Lack of established regulations, focus on one country, applying this technology in different companies or countries might be a problem, risk of data not always being available to check this model
Saurabh and Dey (2021)	Agri food	Blockchain - Hybrid	Not considered	Internal manufacturing and export	Consider as a constant variable	No	Manufacturer ID, manufacturer address, product name, batch ID, source ID, delivery date, quantity, vendor ID, product quality, rules and regulations	Mentioned that only selected stakeholders can access the fully secure data; others have limited access	Discussed under trust and price variables. Performance depends onthe quality of products or services, resources, and capabilities of the focal firm. Measures the cost-benefits.	Pre- and postharvest management, controlled or modified atmospheric storage facility, processing, GPS-enabled transportation and logistics, wireless sensor, less fault tolerance	Difficult to trace from growth of grapes to wineries where the grapes are crushed,compliance issues when working with different countries
Our Method	Covid-19 vaccine	Hyperledger Fabric	Rural, remote and metropolitan ares	Import and internal manufacturing	Develop the smart contract for it and going deeply on the compliance attributes	Yes	Location of vaccine, current time stamp of stock, vaccine name, ingredients of vaccines ingredient providers, stock number, stock count, transaction origin, receiver address, transaction count, tax amount, rules and regulations	Mentioned that only selected stakeholders can access supply chain data	Measures in time and cost: for time, resource availability in time, flexibility, perfect order delivery, for cost, reduces compliance cost, reduces transaction cost, fewer duplicated products and unqualified products	Monitors performance, identifies stakeholders, identifies fake vaccines, solves compliance issues	Still in design stage: not implemented yet

5.0.1. Comparison of proposed Vacledger system with existing literature

This section evaluates the proposed framework’s performance utilizing cost estimation and algorithm complexity.

Table 6 compares the different blockchain-based supply chain traceability studies based on related industries, blockchain type, zone-wise distribution, import, and internal manufacturing, compliance, smart contract built for compliance, traceability/tracking data, transparency, performance scalability, advantages of the proposed system, and limitation of the current approach. To validate our model, we compare our proposed model with a similar blockchain-based supply chain traceability system models developed by Agrawal et al., 2021, Baralla et al., 2021, Cao et al., 2020, Feng et al., 2020, Kuhn et al., 2021, Mangla et al., 2021, Qiu and Zhu, 2021, Saurabh and Dey, 2021, and Uddin (2021).

This study confirms that smart contract build-up for regulatory compliance and border authorization cannot be eliminated when developing blockchain-based supply chain traceability systems. Fig. 14 summarizes their considerations, such as the traceability/tracking data, import, and internal manufacturing, regulatory compliance, border crossing of the vaccines, and smart contract build-up for regulatory compliance and border authorization. However, their results are not very encouraging. Finally, we confirm that smart contract build-up for regulatory compliance and border authorization cannot be eliminated when developing blockchain-based supply chain traceability systems, as shown in Fig. 15.

Fig. 14.

Comparison of performance evaluation of our proposed model with recent blockchain-based supply chain traceability studies using data from Table 6.

Fig. 15.

Comparison of performance evaluation of our proposed model with recent blockchain-based supply chain traceability studies using data from Table 6 (Evaluation criteria: traceability/tracking data, import & internal manufacturing, distribution zone-wise, regulatory compliance, smart contract build for compliance).

Fig. 14, Fig. 15 compare the proposed scheme’s performance in terms of data traceability/tracking, distribution zone-based distribution, regulatory compliance, and smart contract design for compliance. Data was acquired through internal production, distribution, or tracking techniques in most prior studies. While most of their research does not mention importing commodities, several studies demonstrate that the manufacturing material was imported.

Furthermore, the distribution is not shown zone-wise. Using our proposed approach, we may investigate how COVID-19 is spread and tracked throughout the country. Because of these criteria and blockchain implementation, the efficacy of the suggested scheme is relatively high. Moreover, the suggested approach includes a compliance mechanism that is not seen in another research.

5.0.2. Comparison of cost estimation

Every Ethereum transaction costs gas, which is how the network charges for computational resources (CPU, storage). Ether is Ethereum’s native coin. It may be exchanged for local currency, such as USD or EUR, on several cryptocurrency exchanges.

As the value of ether fluctuates in relation to national currencies, so does the cost of gasoline. That is why Ethereum has a gas concept and different gas prices. In this way, even if the Ether price swings greatly, computational expenditures stay constant. This means that every transaction on the Ethereum Virtual Machine is monetary in nature.

The network’s expensive proof of work consensus process is powered by cryptocurrency. This gas cost encourages validating nodes to work. It also discourages hostile nodes from initiating expensive DDoS attacks. Hyperledger Fabric, on the other hand, has no idea of gas. Everyone in the network relates to everyone else. This framework allows malicious persons and behaviors to be easily identified and denied access to the whole blockchain.

A “private” blockchain is intended to function, which means that all network participants know one another. It would be simple to deny access to a malicious peer. There is no mining process, and consensus rules are enabled for each incoming transaction. Compared to Bitcoin or Ethereum, this results in a faster block building operation.

However, it may still use a chaincode that adds a “transaction charge” before confirming each invoked transaction to implement the customized gas system.

• (i)Cost estimates based on existing research

The cost of deploying vaccine smart contracts must be calculated before installing the Vacledger blockchain. The ultimate goal is to build a blockchain-based Vacledger system. More gas is used as smart contract functions/operations get more advanced. We calculate our Hyperledger Fabric gas cost using the gas prices of previously published studies. We calculate the price of imported vaccines supplied to the main distribution; the ingredients provider sends the ingredients to the manufacturer, and the manufacturer sends the vaccines to the main distribution.

Table 7 shows a graphical illustration of the number of transactions involved in each of these scenarios, as well as an estimate of the expenses produced by our system.

Table 7.

Scenario based total transaction cost.

Application	Description
Scenario 1: Imported vaccine transfer to the main distribution center.	Consider importing vaccinations and transferring them to the primary distribution location in a single country. It is required in this environment to deal with external parties as well as rules and regulations. This scenario demonstrates the gas costs for the transfer of imported vaccines to the main distribution center.
Scenario 2: Manufacturer transfer the vaccines to the main distribution.	Let us consider a single country that makes and transports vaccines to a central distribution point. Ingredient suppliers deliver ingredients to manufacturers for production. This scenario assumes gas costs for manufactured vaccines and is distributed to the general public.
Scenario 3: Imported vaccinations and manufacturing vaccines are Manufacture transfer the vaccines to the main distribution.	Some countries, such as Australia, develop part of their vaccines and buy the remaining from other countries across the world. The gas expenses for imported and manufactured vaccinations that are transported to the main distribution are taken by this scenario.
Scenario 4: Imported vaccinations are distributed through the vaccine supply chain.	Certain countries import COVID-19 vaccinations, and domestically manufactured vaccines are disseminated. As a result, it incurs gas expenses for imports, manufacturing, and distribution. Vaccines are transported by zone after being received at the main distribution facility. Hospitals acquire their supplies from Zones. The vaccine supply chain distributes both imported and manufactured vaccines. This scenario demonstrates the gas costs for that.

We obtained data from prior studies (Ahmad et al., 2021, Musamih et al., 2021, Omar et al., 2022, Omar et al., 2021, Yao and Zhang, 2022). However, we approximately choose some values: 50%, 30%, and 20% of the specific cost. For example, “expirationDate” resulted in a total cost of 33,739. This cost includes 50% of imported vaccinations, 20% of ingredient supplies, and 30% of production expenses. Some Values are divided in half, such as “vaccinecode”, which just includes imports and manufacturing costs. Some variables, such as the price of “current-timestamps”, are distributed across the supply chain (External company 18%, Supplier 7%, manufacturer 11%, main distribution 19%, zone distribution 17%, phase 13%, hospital 15%).

The entire cost of gas for each scenario is demonstrated in Fig. 16. It describes calculating the cost of transporting imported, manufactured, or both imported and manufactured vaccines to the primary distribution center. According to Scenario 4, the supply chain for imported vaccinations distributes the vaccines to Phases I–III. It computes the overall cost of gasoline.

Fig. 16.

Comparison of Transaction gas cost scenario wise (Scenario 1 to Scenario 4 as described in Table 7).

5.0.3. Comparison of algorithm complexity

We compare our proposed Vacledger algorithm against supply chain frameworks that utilize Bitcoin, Ethereum, and Hyperledger Fabric. After comparing their algorithm complexity, we observed no differences in complexity between the proposed Vacledger system and current supply chain frameworks based on various blockchain types. Even if the proposed algorithm has more features to handle various events in the blockchain-based supply chain more generously, the new approach does not affect the prior algorithms’ performance complexity Table 8.

Table 8.

Comparative analysis of existing framework complexity with proposed Vacledger framework.

Supply chain frameworks based on blockchain type	Algorithm complexity
Bitcoin blockchain	$\mathcal{O}\left(n^2\right)$
Ethereum	$\mathcal{O}\left(n\right)$
Hyperledger	$\mathcal{O}\left(n\right)$
Proposed model	$\mathcal{O}\left(n\right)$

5.0.4. Security analysis

We explore the critical aspects of the proposed blockchain Vacledger system in overcoming significant security and privacy problems like confidentiality, data integrity, availability, non-repudiation, and vulnerability to cyberattacks in this section.

• (i)Data integrity: It is ensured that no one can edit or remove data stored in a blockchain-based system. Furthermore, data integrity is assured since cryptographic processes are utilized for safeguarding lawful transactions in a block. Assume a distributor or wholesaler makes a purchase order in the suggested system. In such an instance, it will be recorded in the ledger as a valid transaction that is irreversible and cannot be canceled or reversed.
• (ii)Confidentiality: The key characteristics of blockchain secure the participants’ identities, protecting their anonymity. Everyone in the supply chain can see what is happening since all legitimate transactions are time-stamped and kept on the blockchain. Furthermore, eliminating purchase errors necessitates a thorough understanding of the supply chain. For example, under the proposed system, all producers, distributors, and Zones outlining their states are protected, and their identities are protected.
• (iii)Availability: A denial of service (DoS) attack against the blockchain system, for example, is regarded as an attack on the system’s ability to perform. The decentralized structure of blockchain technology allows for this. It is, therefore, feasible to retain all of the blockchain network’s functionalities, such as ordering materials, dispatching, and supplying goods, even while many nodes are missing.
• (iv)Man-in-The-Middle Attacks: Because our solution is built on the blockchain, it inherits all of the characteristics of the technology. All transactions mined on the Hyperledger Fabric network are digitally encrypted to ensure confidentiality. As a result, attackers will be unable to tamper with the transaction since they would want the private key to sign the transaction. As a result, manufacturers would refuse to recognize the transaction and mark it as a block. As a result, the integrity of all communication between the various supply chain entities is maintained throughout the process.
• (v)Non-repudiation: Users cannot refuse a transaction issued or received by a user of the blockchain network. This is useful since the vaccine supply chain network’s wholesalers, distributors, and providers cannot contest incorrectly placed orders. Similarly, manufacturers cannot reject receiving and approving requests for new substances.

6. Discussion

This study’s evaluation is that the private-permissioned blockchain method is beneficial for resolving the significant problems of vaccine traceability in the health industry. The literature indicates a high correlation between performance and transparency. Prior studies have emphasized the importance of the geographical dispersion of a distribution. In our studies, statistics on regulatory compliance build-up for smart contracts or zone-wise distributions were not found in the literature (rural, metropolitan, and remote areas). The comparison Table 6 shows most researchers focused on domestic manufacturing rather than on imported or exported. Agrawal et al. (2021) stated that organic cotton is used for blockchain traceability in the apparel business. The findings may vary by country if other data are added to the blockchain. One limitation is that it shows fear of sharing data owing to shareholder privacy. A potential difficulty is a need for established compliance regulations.

Block generation is delayed as nonce complexity and transactions per block increase, and vaccine quality control is solely focused on internal manufacturing in China. Due to the lack of set norms for vaccine quality control and the use of Ethereum, the Agrawal system is susceptible to virus attacks. Many stream requests were produced in a single instance, which might cause storage problems in Ethereum (Qiu & Zhu, 2021). With its ABCDE method, Agile may be challenging to implement in other sectors because of its emphasis on agri-food and internal production. The industry’s laws and regulations have yet to be described. Although any competitor may view the ledger’s data and verify all transactions in an anonymous version, there are certain limitations to controlling rights by a central authority (Baralla et al., 2021). In contrast to traditional information tracing techniques, a blockchain has effectively traced steel product quality. In other nations, the lack of industrial rules is a major problem. It is difficult to use that approach in other areas.

The blockchain layer relies on the IoT data collection technique (Cao et al., 2020). Validation of that architecture has been done using an Ethereum-based blockchain demonstration, which used a semi fungible ERC 1155 token to demonstrate the logic for automotive product design and process. A lack of defined rules, a denial-of-service assault, or a Sybil attack can create many pseudonymous nodes and data sovereignty (Kuhn et al., 2021). In agriculture, problems may emerge if data are not always readily accessible. However, that research focused only on internal production and did not mention of zone-based distribution regulatory compliance with smart contracts or other existing laws. It may be challenging to use that paradigm in many areas, or nations (Mangla et al., 2021). Although that study concerned grapes collected in rural areas, it examined solely internal manufacturing and excluded zone-based distribution. There was difficulty tracing grape production from the vineyard to the winery where the grapes were grown and crushed. That study offered partial transparency of information. Based on a cost–benefit analysis, the scalability of performance depended on the quality of the products or services as well as the resources and capabilities of the business of interest. It also discussed (Saurabh & Dey, 2021) trust and pricing factors. Working with various nations has its own set of regulatory compliance challenges.

Individuals, regardless of their level of education, wealth, or social standing, are vulnerable to incorrect information and must be vigilant against the flow of possibly misleading information. To combat the development of counterfeit vaccines, governments, pharmaceutical companies, regulatory agencies, and law enforcement must collaborate to eliminate disinformation and establish reputable information sources to fill the void (Amankwah-Amoah, 2022). In addition, using emerging technology, such as artificial intelligence, deep learning methods, and social media, to tackle misinformation about the COVID-19 pandemic may aid in limiting the issue.

One possible use of blockchain in the supply chain is to increase transparency and traceability. There are also several other possible uses for blockchain in the supply chain, such as minimizing the need for intermediaries, enhancing the security of transactions, and developing new business models and income sources. A recent study (Halgamuge, 2022) indicates that a probabilistic strategy is suitable for protecting rapid and real-time machine-to-machine interactions by evaluating the probability of a malicious attacker’s success on a blockchain. As the technology continues to evolve and become more widely adopted, it is anticipated that supply chain applications for blockchain will increase.

Finally, L-IoT is an emerging technology that has substantial potential to enhance supply chain traceability. Its use in the distribution of vaccines during the COVID-19 pandemic has proven its significance in guaranteeing the secure and efficient delivery of essential medical supplies. Overall, Logistics IoT may enhance supply chain traceability and facilitate more efficient and dependable operations. When used in association with blockchain-based smart contracts, as our proposed COVID-19 vaccination supply chain management, it may also aid in the prevention of counterfeiting and assure the authenticity of goods. However, further investigation is needed to explore the full potential of L-IoT in supply chain management, especially in the pharmaceutical industry.

In order to develop regulatory compliance and an automated border clearance system for cross-border authorization, it is necessary to adopt policies, standards, specifications, legislation, and an automated system. Partnership with experts and stakeholders, usability, and continuing training and support are essential for successful implementation. In our study, we include new regulatory compliance (policy, standard, specification, or law) smart contracts for cross-the-border authorization.

6.1. Managerial implications of our study

The complexity of the supply chains and the unpredictability of the operations make an organization more susceptible to interruptions. The engagement of stakeholders is necessary for more resilient vaccine supply chains (Kazancoglu, Sezer, Ozbiltekin-Pala, & Kucukvar, 2022). Consequently, it is vital to examine the management consequences, as shown below:

• (i)Enhanced Supply Chain Administration: Blockchain-based Vacledger system improves supply chain management. It lets management monitor vaccines in real-time from origin to destination and ensures they must be delivered at the right time and location.
• (ii)Increased Data Transparency: Proposed blockchain-based vaccination supply chain transactions are transparent and tamper-proof. Thus, managers can easily validate vaccination and trace suspicious behavior. This also reduces fake vaccines and improves data openness.
• (iii)Reliable Vaccine Distribution: Vacledger helps managers improve vaccination distribution depending on demand and availability. Managers may deploy vaccinations to high-demand regions by examining vaccine distribution data. Thus, this ensures vaccines reach the target population effectively and on schedule.
• (iv)Compliance with Requirements of Regulation: Vacledger helps managers meet vaccine distribution regulations. It keeps a tamper-proof record of transactions that may be audited for regulatory compliance. This allows managers to avoid vaccine distribution legal and regulatory difficulties.
• (v)Improved Security: Proposed Vacledger’s distributed ledger prevents hackers from altering data. Thus, this protects the vaccine supply chain against counterfeiting and aids managers in providing original COVID-19 vaccines.

In summary, this may assist managers in enhancing supply chain management, enhancing data security, optimizing vaccination distribution, and meeting regulatory requirements.

6.2. Challenges in blockchain-based smart contract implementation

In the health sector, where vaccine-related tracking and authenticity are essential problems to be addressed using blockchain-based solutions, the implementation, and adaptation of blockchain technology incur severe deployment and adaptability problems. Table 9 highlights some current problems confronting smart contracts (for example, Hyperledger Fabric) and corporate organizations.

Table 9.

Challenges in blockchain-based smart contract implementation.

Challenge	Description
Regulatory compliance	Blockchain-related policies and guidelines must consider the uses and implicationsof blockchain technology, distributed storage, ownership of blocks, and record-keeping on the ledger. Moreover, those who control the block, the information in it, and the various access permissions and rights on the blockchain network need to be considered.
Lack of standardized regulations	Eachparticipating organization plays an essential role; however,all participants in the supply chain must ensure pharmaceutical quality, safety, efficacy, transfer, and exchange. Vaccine-related data may be securely sent, stored, retrieved, and shared in a transparent, accessible, and interoperable way to offer many useful healthcare solutions. Health authorities may struggle to identify their authority and the proper legal responsibilities for the parties when one new vaccine transaction is done on the system. For blockchain systems, another problem is adjusting to new regulations, such as those under development by regulatory agencies like the FDA or the European Union (General Data Protection Regulations). As a result, blockchains still have much room forimprovement regarding current healthcare legislation and regulations.
Data privacy	The concern with data privacy is that many stakeholders worry that they may lose their competitive edge.Consequently, they may avoid joining the network for fear of becoming obsolete.
Cost	It is difficult to locate and choose the most suitable blockchain platform because most projects are not practically fully built. Some of the most significant obstacles organizations face in allowing the effective management of vaccine, traceability are implementation and operating costs.

6.3. Future works & limitations

• (1)Enhance the Vacledger system by adding patient data to the system Using a Vapp, the patient may see where the vaccine is located. Additionally, we may use the patient’s information to increase the development of the Vacledger using the vaccinator and injection records, respectively. Vaccine data can be entered into the Vacledger system using a smart contract called the vaccine information recorder: 1. Vaccinator ID number; 2. COVID-19 vaccine name; 3. Vaccinator name specifications; 4. Vaccinator sex; 5. Inoculated COVID-19 vaccine batch; 6. Vaccinator age; 7. Date of vaccination; 8. Vaccinator’s past medical history; 9. Vaccination place; 10. Vaccinator phone number; 11. Vaccinator address; 12. Extra details and information; 13. Vaccine batch number, those details can be added to the smart contract.
• (2)Data-sharing legislation and incentives with the Vacledger system Even though Vacledger looks to offer scalability, privacy protection, and system security, current medical institutions and the general public have concerns about sharing data. Firstly, the lack of vaccination data laws and legislation is an issue. Secondly, stakeholders’ sharing, and use of information hinder vaccination data exchange. Several potential work approaches address public concerns regarding Vacledger’s data sharing. First and foremost, legislative initiatives are necessary to manage data sharing and governance. Regulations are required that precisely clarify how and with whom data should be shared, and which aspects of that data should be shared. Blockchain may play an essential role in regulating and standardizing data exchange. It is possible to make data exchanges more transparent and accountable, for instance, using of traceable blockchain. Second, blockchain has the potential to accelerate data exchange. For example, using blockchain’s built-in incentive/pricing mechanisms, the general public or patients may be motivated to share their vaccination data. Medical and scientific groups may be interested in purchasing the information provided. It is worth emphasizing that data privacy protection techniques are still required for vaccination data transmission.
• (3)Vacledger scalability and efficiency COVID viruses constantly mutate; consequently, numerous novel COVID vaccines are feasible. In the future, most countries are attempting to purchase such vaccinations. As a result, Vacledger sets excellent demands on blockchains’ speed and storage capacity. Consequently, examining blockchains in terms of scalability, throughput efficacy, and modularity will be a crucial research emphasis in the future. The present blockchain systems may become overburdened because of the increased data volume. There are various options for resolving this issue. Using a novel blockchain data storage technique, such as on-chain and off-chain storage, on-chain data redundancy and synchronization difficulties may be avoided. After determining the optimum performance characteristics, such as the encryption scheme, block size, and block interval, consensus techniques can be tweaked. A consortium chain, for example, might increase transactions per unit time by combining private and public blockchains. Due to the modularity of blockchains, it is also feasible to deconstruct and reassemble blockchain systems without compromising the integrity of Vacledger system data. It is required to develop smart contract deployment methodologies to achieve modularity.
• (4)Integration of Artificial Intelligence (AI) with the Vacledger framework In the vaccination supply chain, malicious intrusions are a significant danger. AI may be used to detect potential flaws in the Vacledger system. Errors and fraudulent data sets are no longer an issue. The authenticity of AI-generated classifiers and patterns may be verified via decentralized blockchain technology. The vaccine data may then be mined for hidden value using AI technology, allowing for a complete evaluation of the data in the Vacledger system. The artificial intelligence platform can find important information from vaccination stock data, historical purchase data, and other sources to identify Vacledger data features and perform predictive analysis, such as Vacledger’s future demand projections, sales model forecasts, route planning, and network management.
• (5)Privacy-preserving big data analytics of the Vacledger system The Vacledger system can preserve patient privacy while simultaneously making it easier to work with massive amounts of data. It is possible to analyze encrypted data with attribute-based encryption and blockchains. Vacledger systems in the future will be able to extract more relevant data while maintaining data privacy using big data approaches.
• (6)Experimental data When we calculated the Vacledger supply chain transaction gas cost, the experimental data was drawn from several prior investigations. As a result, when all data is considered in a single flow, the results may slightly differ from reality.

7. Conclusion

This study has explained the major importance of developing supply chain traceability and counterfeit detection system in the healthcare system. The current study aimed to develop a novel private-permissioned blockchain-based framework, Vacledger, for supply chain traceability and counterfeit detection to track COVID-19 vaccines. The results of this investigation show that the proposed four smart contracts can be utilized to (i) handle the rules and regulations of vaccine-importing countries and provide authorization for cross the borders (regulatory compliance and border authorization smart contract), (ii) register new and imported vaccines in the Vacledger system (vaccine registration smart contract), (iii) find the number of stocks that have arrived in the Vacledger system (stock accumulation smart contract), and (iv) identify the exact location of the stock (location tracing update smart contract). The evidence from this study suggests that stakeholders could utilize the proposed blockchain-based Vacledger system to participate in verifying and validating supply chain transactions securely. Taken together, these findings suggest a role for private-permissioned blockchain in promoting a secure health industry and avoiding counterfeit medicine and vaccines. When calculating the gas transaction cost for the Vacledger supply chain, we rely on experimental data from many prior studies. Thus, the findings deviate slightly from reality when all data is evaluated in a single flow. This study utilizes the COVID-19 vaccine supply chain (healthcare) to illustrate the functionality of the proposed Vacledger system. Given this, our suggested method might be applied to various supply chain industries, including food, energy, and commodity trading. This study’s findings have significant implications for future practice. Firstly, governments and regulatory agencies demand transparent supply chains and traceable goods. This will probably include utilizing the proposed Vacledger tool to generate an immutable record of the product movement. Secondly, supply chain rules will likely focus more on monitoring and supervising third-party providers. Our smart contracts could be utilized in evolving these supply chain policies and regulations in addition to monitoring and supervision of third-party providers.

CRediT authorship contribution statement

Uvini J. Munasinghe: Data curation, Writing – original draft. Malka N. Halgamuge: Conceptualization, Methodology, Writing – review & editing, Supervision.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Biographies

Uvini J. Munasinghe received the M.Sc. in Network Security and Business Analysis from the School of Computing and Mathematics, Charles Sturt University, Melbourne, Australia. She completed her bachelor of statistics degree at the Sabaragamuwa University of Sri Lanka in 2017. Her current research interests include blockchain technology, business analysis, and network security.

Dr Malka N. Halgamuge is a Senior Lecturer in Cybersecurity at RMIT University, Melbourne, Australia and the Chair of the IEEE Computational Intelligence Society, Victorian Section. From 2007-2021 Malka worked as a Researcher at the Department of Electrical and Electronic Engineering, The University of Melbourne. She obtained her PhD in the same department. She was awarded prestigious fellowships to work at Lund University in Sweden, UCLA in Los Angeles, USA, and the Chinese Academy of Sciences (CAS) in Beijing, among others. She is passionate about research in emerging technology, cybersecurity, IoT, edge computing, power grid security, supply chain security, blockchain, and developing solutions using deep/machine learning.

Data availability

No data was used for the research described in the article