Table 3.

Literature data of the included studies (n = 8)

Author (Year)	Type of study	Scope/Issues	Blockchain application/implications for vulnerable populations
Rodima-Taylor (2018) [ 15 ]	Not explicit, but authors state “In this article, we explore the implications of digital ledger technologies for global networks of value transfer and verification.”	Lack of identity Financial transactions	Estonian e-residency programme, “provide a government-authenticated digital identity to foreigners”, “Offering a transnational digital identity to citizens of any part of the globe, it allows anyone outside Estonian borders to engage in commercial activities with public and private sectors, using a ‘platform built on inclusion, legitimacy and transparency’.” “provide secure digital identity for KYC compliance and a digital fiat for currency conversion”, “reduce the costs of cross-border fund settlement in remittance transfers”, “replace corresponding bank chains (…), significantly lowering the costs and duration of remittance transactions.”
Blue (2019) [ 16 ]	Not explicit, but authors state “This paper outlines the design and initial development of a solution that could potentially allow refugees who are resettling to build a digital identity document over time as they settle in a new land, without the need for multiple sources of traditional identity documentation.”	Lack of identity	“design of an algorithm that aims to authenticate or refute identities based on information gained from digital footprints.”, “construct a secure and intelligent digital identification document.”, “allow individuals to assert their identity without requirement for traditional paper documents or electronic records.”
Abraham (2019) [ 17 ]	Not explicit, but authors state “This paper follows four activist projects (...) and the effort to build a database for undocumented Rohingyas using blockchain”	Lack of identity	“give undocumented Rohingya a digital identity through the creation of a virtual database”, “build (..) a decentralized and encrypted means for people to engage in online collective activities.”, “enable each registered person to be identified uniquely, giving them a digital identity that is secure and independent of state controls.”
Wiatt (2019)[ 18 ]	Blind peer review	Lack of identity. Academic records	“store, validate, and access [identity and academic] degrees and certificates from remote devices.”
Khurshid & Gadnis (2019) [ 19 ]	Policy proposal	Lack of identity Health records	“create profiles for persons experiencing homelessness, using biometric features.”, “secured, immutable identity created for every individual in the program.” “allow persons to access their health data and details”, “record all their transactions with health providers and emergency medical services through the same ledger.”, “allows individuals to have direct access to all transactions that are recorded on the platform through any interaction in the system while also allowing each agency to access that record with permission of individuals.
Seyedsayamdost (2020) [ 20 ]	Not explicit, but the authors state “This paper examines three projects that have piloted DLT use cases, (…) explores the use of blockchain technology with a view to understanding its implications for governance”	Humanitarian aid, Lack of identity Humanitarian aid, Financial transactions	ConsenSys- Moldova, “create digital identities and expand access to verifiable identification while improving security over personal data (…) that relies on biometric identifiers, including fingerprints and iris scans, which can protect minors from trafficking.” WFP’s Building Blocks, “treamline delivery of food and cash, particularly in crisis situations where speed is of utmost importance and the financial infrastructure has been disrupted and is ineffective in the delivery of life-saving resources”, “facilitate financial inclusion for billions of people by not only enabling the creation of a digital identity but also allowing people to directly transact with others.” Moeda “offers impact investors the opportunity to make capital available to those in need, while being able to expect a return on their investment, and a reasonable degree of liquidity.”
Christ (2021) [ 21 ]	Not explicit, but the authors state “The purpose of this paper is to offer a conceptual discussion as to how a relatively new technology, the blockchain, might be used to reduce vulnerability and risk in migrant worker populations.”	Lack of identity, Migrant labour exploitation	“provide [migrant] workers with a clear record of their identity which can then be linked back to their visa and contract of employment. Such evidence will provide protection against confiscation of identity documents which can be used as a form of blackmail to prevent workers from leaving unacceptable working arrangements and lead to forced labour”, “record and provide an auditable trail of transactions associated with labour recruitment, such as employment contracts, migration details, passports and visa arrangements”, “provides a way to ensure the initial contract terms are permanently, immutably recorded for anyone to see.”
Shuaib (2021) [ 22 ]	Not explicit, but authors state “This paper reviews the aspects of SSI application during the pandemic situation like COVID-19.”	Lack of identity, Access to health, Health records, Covid-19 assistance	“creation of a blockchain-based self-sovereign identity with the potential of providing medical information could significantly affect the migrants lacking on lawful documents”, “provide access to undocumented people’s fundamental rights, which should become standard and even more critical in regularly responding to crises”, “self-sovereign identity-based immunity credential to offer the tracing and tracking of COVID-19 test-takers”, “digital credentials will provide the patients with verifying their health conditions and immunity against various diseases”, “fight and control the outbreaks of COVID-19”