Exploring the scope and utility of digital proximity tracing in the effective containment of COVID-19 infection: A narrative review

Abstract

The ongoing coronavirus disease-2019 (COVID-19) pandemic can be acknowledged as one of the most significant public health emergencies the world has encountered in the last few decades. The purpose of the current review is to understand the significance of contact tracing and explore the pros and cons of digital contact tracing in ensuring better containment of the COVID-19 outbreaks. A widespread search of published articles pertaining to the topic was done in the PubMed search engine and a total of 46 articles matching the objectives of the present review were identified. However, four articles were discarded because of the non-availability of the free full text, and thus 42 research papers were finally included. Digital contact tracing bridges the gap wherein we aim to expedite the process of contact tracing to identify the potential contacts of the confirmed cases. These applications are designed in such a way that they send a notification on the smartphone of a person, once the user is exposed to one or more confirmed cases of COVID-19. To conclude, in the battle against the COVID-19 infection, the international welfare agencies and national policy makers have been looking forward to the employment of digital technologies to support the ongoing public health measures for contact tracing. The approach of digital contact/proximity tracing should be considered as a supplement to conventional manual tracing. The need of the hour is to take specific measures to improve the inherent design of these apps, their implementation and demonstration of their effectiveness, which in turn will play a part in enhancing their acceptance and usability among the general population.

Introduction

The ongoing coronavirus disease-2019 (COVID-19) pandemic can be acknowledged as one of the most significant public health emergencies the world has encountered in the last few decades.¹ This can be clearly ascertained from the very fact that since the start of the outbreak until 3 April 2022, more than 600 million confirmed cases and in excess of 6 million deaths have been reported worldwide.² The reported threat was not only in terms of loss of human lives, but the disease has accounted for a major impact on the mental, social, financial, professional, and various other domains of life, including the impairment of overall quality of life.³

Realizing the impact of the disease, a number of strategies have been introduced to ensure better prevention and control of the novel viral infection, including the introduction of rapid diagnostic tools, improvement in contact tracing, better patient management, strengthening of the health care delivery system, risk communication system, community awareness activities, intensification of the research and development activities, implementation of infection prevention and control measures, imposing lockdown, etc.^4-6 Digital contact tracing is a specific type which is implemented using tracking systems, preferably mobile phones, with a purpose to ascertain the contact between an infected person and close contacts. The purpose of the current review is to understand the significance of contact tracing and explore the pros and cons of digital contact tracing in ensuring better containment of the COVID-19 outbreaks.

Review methods

A widespread search of published articles pertaining to the topic was done in PubMed. Subsequently, the research papers targeting digital contact tracing amid the ongoing COVID-19 pandemic published in the years 2020 and 2021 were considered for the current review. We found 46 articles matching the objectives of the present review, of which four were discarded because of the non-availability of the free full text. Moreover, only the research papers published in English language were considered in the present review. Thus, 42 research papers were finally included as they were in alignment with the current review objectives (Figure 1).

Figure 1. Flowchart for selection of research articles.

Keywords used for the search include digital contact tracing and COVID-19 in the title alone only (viz. COVID-19 [ti] AND mobile [ti]; COVID-19 [ti] AND contact tracing [ti]; digital contact tracing [ti]; COVID-19 [ti] AND digital contact tracing [ti]; COVID-19 [ti] AND digital [ti]; digital proximity tracing [ti]; COVID-19 [ti] AND proximity tracing [ti]; COVID-19 [ti]). The collected information is presented under the following sub-headings, namely Contact tracing, Digital contact tracing, Functioning of digital proximity tracing apps, Digital proximity tracing apps: Bridging the gap, Limitations and additional considerations, Experience from different nations, and Implications for research.

Contact tracing

Contact tracing has been identified as one of the most crucial strategies to interrupt the chain of transmission by identifying the potential suspect cases.^7,8 This is generally followed by isolating the close contacts of a confirmed case of COVID-19 and performing laboratory diagnostic tests.^7-10 We must acknowledge that prompt action on our part can prove to be a life-saving intervention and is also crucial to minimize the spread of the infection.^3,8 Any inability on our part to trace the asymptomatic infectious cases or new cases will account for the silent transmission of the infection in the community, which eventually can overwhelm the healthcare delivery system.^8-11

The findings of a study done on a ship in Japan revealed that 70% of the transmission occurred before the first case became symptomatic.¹² The mathematical models further depicted that a delay of more than 3 days in notification of the infection might account for an outbreak that becomes difficult to contain.^13,14 In other words, the process of contact tracing should be very quick, otherwise the outbreak can become very large. In such settings, the conventional strategy of contact tracing will not deliver the desired results as the number of cases continues to rise at an exponential pace.¹⁵ Moreover, we cannot ignore the fact that it is a challenging task to reach potential contacts during times of sudden surge in the number of cases, as the healthcare delivery system becomes overwhelmed. Thus, we have to resort to digital forms of contact tracing to expedite the public health emergency response of the health sector.^16-18

Digital contact tracing

The concept of digital contact or proximity tracing attracted significant attention as the policy makers, program managers, and healthcare workers were taking all measures to interrupt the chain of transmission.^16,17 Digital contact tracing bridges the gap in expediting the process of contact tracing to identify the potential contacts of the confirmed cases.^17,18 This can be done using a wide range of technologies (based on location, geospatial attributes, proximity awareness, machine algorithms, etc.).^10,13 These technologies aid in ascertaining the digital footprints, tracing the people who are infected, localizing the contacts, and thus providing the desired information to policy makers to plan and implement specific strategies to alter the dynamics of disease transmission.^18-20

It has been anticipated that the combination of digital and conventional contact tracing can play a significant role in interrupting the chain of transmission of the causative virus and thus slow down the community transmission.^19,21 Digital proximity tracing has been linked with multiple merits such as reduction in the overall response time when compared with manual tracing, which in turn enables early identification of the people exposed to the causative virus.^13,21,22 Thus, these applications enable fast notification of contacts, and prompt quarantine of the identified contacts. In addition, these apps can continue to function in the community, even when the health services engage with managing patients in healthcare establishments.²³

Further, these apps do not rely on the memory of the positive person about their all contacts (ruling out recall bias), and this makes the overall process comprehensive.²³ To summarize, these applications enable the health sector to quickly interrupt the transmission chain before the number of cases increases to such an extent that it overwhelms the healthcare system.^13,21,22 These forms of digital proximity tracing have been carried out using a wide range of technologies, mobile applications, geographical information system-related mapping, etc.^21,22

However, we must realize that a significant amount of variability has been reported across different settings, in the terms of installation (voluntary vs compulsory), data management strategy, technology used (e.g. GPS, Bluetooth, or quick response codes), algorithms deployed in the back end (if any), level of human oversight, the degree of interaction with users, etc.²⁴ On a technical note, digital contact tracing is not an appropriate term, as most of the available applications provide details pertaining to exposure notification.²⁵ These exposure notifications make people feel safe and as if they are living in a protected community, nevertheless as personal details are released (which are accessible to everyone in the neighboring vicinity), questions have been raised about public trust.²⁵

Functioning of digital proximity tracing apps

These applications are designed in such a way that they send a notification on the smartphone of a person once the user is exposed to one or more confirmed cases of COVID-19 (provided these confirmed cases are also using the application).²³ The exposure, in this case, is defined as a contact with a confirmed case for 15 minutes or more with proximity of less than 1.5 metre.^23,26 If these conditions are met, the person will receive the notification, which is mostly Bluetooth driven. Subsequently, these contacts will also get information about the further actions that need to be carried out by the potential contacts, including advice for quarantine and laboratory testing.^23,26,27 Most of these apps are designed in such a way that they can safeguard the privacy of the user. Finally, some or other variations might be present in different nations, but the basic principles remain the same.^22,26-28

Digital proximity tracing apps: bridging the gap

In general, the conventional form of manual contact tracing begins once a person is diagnosed with COVID-19, we go back and start looking for the potential contacts.²³ However, we cannot rule out the very fact that people are infectious 1-3 days prior to the actual onset of symptoms. In other words, the manual contact tracing begins a bit late.^23,29 These digital proximity tracing apps come into the picture the moment a person is diagnosed with the infection, and all the potentially exposed users get a notification on their app about the same.^27-29 In other words, before a health worker reaches the potential contact physically or telephonically to the exposed potential contacts, they have already received the alert and they can initiate the necessary prevention and control measures to break the chain of further transmission.^23,28-30 To complete, these apps also play an important role in expediting the work of manual contact tracing.¹⁹

Limitations and additional considerations

The overall effectiveness of these digital proximity tracing apps will be determined by the proportion of the population who is actively using these apps, the ability of the employed technology (such as Bluetooth) in precisely calculating the distance, and the fact that not all people can use (because of the absence of smartphones or limited abilities to use digital tools) or will be willing to use these applications.^31,32 The willingness of a person to use these proximity tracing applications can be influenced by lack of trust, uncertainty about their effectiveness, absence of internet accessibility, etc.^31-34 Thus, the application developers should take into account all these aspects and try to respond accordingly.^23,32,35

It is extremely important to ascertain the utility of these applications and evaluate them in terms of their public health significance.^36,37 These applications have to improve their communication strategy, especially in difficult-to-reach settings, and should encourage isolation of the infectious people precisely.³⁶ There is also a need to assess the time these applications take to notify the people about the presence of a positive case, as any delay in this regard will eventually compromise the basic purpose of reducing the transmission of the infection.³⁶ The acceptance among the general population can be enhanced by keeping the apps transparent.³⁶ In fact, we have to compare the utility of these apps in terms of the claims they make and the actual results obtained through their use.³⁶

Experience from different nations

As the number of COVID-19 cases was rising at a rapid pace, it was decided that contact tracing will prove to be an important strategy for the effective containment of the infection.^7,9 Keeping this in mind, different nations started on working applications to fast-track the process, as interview-based contact tracing was difficult to execute owing to the reallocation of health workers towards other aspects of the care.^8,38 In a study done to ascertain the impact of the National Health Service COVID-19 app for England and Wales, it was reported that 28% of the total population accessed the application.³⁷ However, it proved to be quite effective among these users, as approximately one case was averted for each case consenting to notification of their contacts.³⁷

Significant progress was made in Switzerland in this regard and they came out with the SwissCovid digital proximity tracing app, which was based on Bluetooth application, and this application delivered encouraging results.^39,40 On similar lines, in India, we adopted the Aarogya Setu app, which was a mobile-based application, and that not only aided in contact tracing but even made the people aware of various other positive cases in the neighboring vicinity.⁴¹ The Aarogya Setu app was found to be extremely helpful in identification of the cases and limiting the spread of the infection by giving a warning signal to the other people in the neighboring vicinity.⁴¹

Implications for research

As digital proximity tracing apps are still in their early stages, a lot of research needs to be done to explore their utility.⁴² The effectiveness of these applications will be determined by the confidence which general population will have in them and based on the privacy of the data.^23,43 In addition, there is a need to explore the various attributes of the app, like attainment of the intended objectives (the capacity of these apps to detect contacts), user-friendly nature of the employed technology, the speed with which this technology can notify contacts, and the acceptability among the people.^32-34,42-44 All these domains can be assessed by carrying out a questionnaire-based study or preferably qualitative research, wherein different stakeholders can be interviewed to get insights about the pros and cons of such applications. Further, we require specific research work to assess the speed with which this technology can notify contacts.

Conclusions

To conclude, in the battle against COVID-19, the international welfare agencies and national policy makers have been looking forward to the employment of digital technologies to support the ongoing public health measures for contact tracing. The approach of digital contact/proximity tracing should be considered as a supplement to conventional manual tracing. The need of the hour is to take specific measures to improve the inherent design of these apps, their implementation and demonstration of their effectiveness, which in turn will play a part in enhancing their acceptance and usability among the general population.