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Blockchain can answer immunity passport security concerns, but any roll-out must be dictated by the science

(Image credit: Image Credit: Zapp2Photo / Shutterstock)

As Covid-19 continues to sweep across the planet, governments everywhere have been forced to battle an invisible enemy. This has led to the widespread sacrifice of civil liberties, with some demographics being bound to their households for well over a month. 

However, it has also ignited a reassessment of the role that technology can play and citizens’ right to privacy. This is particularly the case in the ongoing development of contact tracing apps, which have been heralded by some as the golden tickets out of the pandemic.

Yet, a rather mooted but just as important tool that has been suggested as one way of bringing the crisis under control are so-called ‘immunity passports’ – a topic that requires some further consideration in the ongoing review of the role that technology can play in ending this crisis.

What are immunity passports and how could they work?

The basic idea of an immunity passport is to link an individual’s identity with their Covid-19 test status, allowing those who have recovered from the virus to return to work and help restart the economy. In other words, an immunity passport would rely on antibody tests – which are intended to show whether someone has recovered from the infection – to then provide certification that a person is immune and cannot catch the virus again. 

However, with this concept still a work in progress, the practicalities of how it could be enacted are still under debate.

A first scenario could be providing citizens with a certified, paper-based passport, similar to the one they use to go on holiday and cross borders. Contrastingly, backers of the idea say that those who qualify could receive digital certificates, also known as ‘digital immunity passports’, displayed like smartphone boarding passes. For example, it has been suggested that users could submit a photo of a government-issued form of identity, such as a driving license, to a dedicated app. A facial recognition system would then scan the images to confirm they match and then their identity would be linked to their test result. They could then present this app whenever they are required to prove their immunity.

However, a key concern relating to immunity passports is that, if an individual needed to prove their health status, that information would need to be unalterably linked to their identity for it to be considered acceptable and the risk of the virus spreading kept to a minimum. Inevitably, this makes paper-based approaches less likely to satisfy the stringent security and data protection protocols required to ensure health data is both protected and unalterable. 

Secure and tamper-proof

With this in mind, the concept of digital immunity passports has some purchase to it, but only if it harnesses the latest technologies, such as blockchain. 

A blockchain can be best defined as a shared, distributed database which records transactions. Each transaction is added as a block and is stored, decentralised in the chain. Importantly, this means that no central party has control over its content, and nobody can tamper with the records because every member has to agree to its validity and can check the history of record changes.

If this technology were to be at the centre of any digital immunity passport development, not only would it ensure that the end-user remains in complete control of how their health data is being used, but it would also give employers and other stakeholders peace of mind that this data is unalterably linked to their identity.

For example, a blockchain-enabled immunity passport could work if end-user’s provide proof of ID before testing and a permanent digital fingerprint of the double-signed certificate is placed on the blockchain, which is used by a verifier, such as an employer, to check authenticity. Crucially, as sensitive medical data, such as Covid-related test results, is stored as a ‘fingerprint’, this offers a form of encryption and ensures that the digital certificate provided to the end-user is secure and tamper-proof by design, which means it is unalterably linked to their identity.

This could have a number of important consequences in the pursuit of some sense of normality. Firstly, providing citizens with access to an unalterable, digitised blockchain-enabled immunity passport would give them a form of secure, portable credentials that they could share with anyone, including their employers and authorities, at any point to prove they are immune from Covid-19. For those more concerned about the security of personal data, as each fingerprint is individual and does not reveal any information about who the document belongs to, it also safeguards the information it contains.

Further, looking beyond the crisis the immunity passport secured by blockchain can help better prepare for the future and serve as a tool to manage any new wave or seasonal reoccurrence of the epidemic. Once a vaccine for Covid-19 is found, it could also be the cornerstone of a future secured digital vaccination record.

A word of warning: the science must dictate any passport rollout

Before we get ahead of ourselves, however, a strong dose of caution needs to be caveated here. For one, the immunity tests need to possess high levels of sensitivity and specificity which are essential measures to express the rate of false negatives and false positives of a result. Whereas the former could be seen rather as bad luck for the individual not revealing their true immune status, the latter could turn into a communal health hazard as the person believing to be immune is in fact not and might still get infected and subsequently spread the disease to others.

To make this matter even more complicated, the true quality of the test is correlated to the existing prevalence of immunity in the population through the application of the Bayes’ Theorem from probability and statistics: The higher the share of people in the population who had been previously infected, the higher the hit rate of the test. Unfortunately, also the inverse holds true.  For the other, even more general point to immunity: The World Health Organisation (WHO) has consistently warned about a lack of scientific evidence for Covid-19 immunity, saying those who wrongly believe themselves to be immune could get reinfected or transmit the disease further. At present, scientists simply don’t know how long someone remains immune to the coronavirus — or even if they can become immune at all.

This has the potential to derail the concept of digital immunity passports entirely.

As such, a more sensible line of action would be to follow the science; for a blockchain-enabled immunity passport to truly work effectively and be taken seriously, it is crucial that the antibody test is proven to show that end-users cannot get infected again. However, this should not mean that government’s and healthcare bodies abandon the development of digital immunity passports altogether, as the time may come when this sort of technology could be highly effective and has to be rolled out quickly.

René Seifert is co-founder of and Chief Digital Officer at The DataFlow Group