Health certificates for COVID-19: what our review of research evidence implies for UK ‘vaccine passport’ policies

COVID-19 vaccine passport concept

Professor John Drury, co-author of the first rapid review of evidence on the behavioural effects of COVID-status certification, describes the review’s key findings and asks: how might trends emerging in ‘early-adopting’ countries inform UK policy decisions?

Reasons for concern amid the potential benefits

COVID-status certification – certificates based on vaccination status, tests for infectiousness, tests for the presence of antibodies, or a combination of these – has been proposed by a number of governments as a way of opening up more areas of activity in society while minimising risk of transmission, by reducing the number of people in a space that are likely to be infectious. Such certification could be applied to access to a range of different activities, including the more occasional (international travel and attending live events), the more ‘everyday’ (such as going to a pub or restaurant), and the essential (workplaces).

Particular attention has been focused on the possible ethical and legal problems with COVID-status certification. Our recent rapid review of research evidence focused on behavioural responses to COVID-19 health certification, as there are possible reasons for concern here as well as the potential benefits.

Our global review, carried out in December 2020, identified 33 relevant papers on behavioural responses to COVID-status certification. In all, we assessed evidence from 10 countries: UK (10 studies), Germany (9), US (3), Australia (2), Canada (1), Nigeria (1), Poland (1), Romania (1), Spain (1) and Switzerland (1).

The 10 questionnaire surveys we reviewed found that public attitudes were generally favourable towards the use of immunity certificates for international travel, but unfavourable towards their use for access to work and other activities. A significant minority of those asked were strongly opposed to the use of certificates of immunity for any purpose.

One of the arguments made for COVID vaccine passports is that they will encourage more people to get vaccinated. However, the limited evidence we found suggested that intention to get vaccinated varied with the activity enabled by vaccine certification – with visits to a nursing home and international travel being the most popular reasons.

Certification could also have ironic effects. For example, some surveys suggested that restricting access to certain settings and activities to those with antibody test certificates may lead to deliberate exposure to infection among a minority of people. Other studies suggested behaviours that reduce transmission, including physical distancing and handwashing, may decrease upon receipt of health certificates based on any of the three indices of COVID-19 status.

How people have responded to certification schemes

Our rapid review of evidence on possible behavioural effects of certification is the only one of its kind carried out so far. But perhaps the main conclusion is that few implications can be drawn from it in relation to policy and practice. The existing research evidence (at least at the time of our review) is extremely limited in both quantity and quality.

Almost none of the studies actually observed behaviour, and almost none examined actual existing certification schemes. Rather, studies typically asked people hypothetical questions in surveys (or experiments). And the potential for the use of health certification to exacerbate existing inequalities – one of the main objections made by critics of certification – was not addressed at all in the studies we found.

In order to help inform policy on this topic, it’s therefore necessary to look at how people have responded in relation to existing COVID-status certification schemes. Many countries are planning or trialling such schemes, including Germany, France, and Spain.

Denmark’s scheme started with access to zoos and theme parks; bars, football stadiums and restaurants will be next. Reports suggest there is public support for the scheme. It seems relevant to note that while only a fifth of the population have so far been vaccinated, Denmark has a higher rate of testing per capita than any other country worldwide.

The country with the most well-established and well-documented COVID certification scheme is Israel. That country’s ‘green pass’ scheme (which works through an app that shows whether people have been fully inoculated or have already had the virus) allows access to gyms, hotels, theatres and concerts.

The rate of new COVID infections has plummeted in Israel; restaurants, bars and theatres are busy, and there are other signs of pre-pandemic life returning. It is not clear, however, to what extent COVID certification has been responsible for the relaxation in that country; some reports suggest green passes are not always checked at restaurants and other venues.

The vaccine roll-out in Israel has been one of the fastest in the world (though it has not reached Israeli Arabs or Palestinians to the same degree). But while some hoped the scheme would operate as an incentive for vaccination, the country’s programme of community engagement (including taking mobile vaccination units into communities and bars and working with trusted local leaders) seems to have been more important for the rates of uptake.

Implications for UK policymakers

By their nature, COVID-status certification schemes exclude some people just as they increase the freedoms of others. In the UK, given that both participation in testing and uptake of vaccination is lower in ethnic minorities and deprived groups, certification will disproportionately exclude these groups from those areas of activity that require a certificate. In short, inequality and inequity is likely to be a result of COVID-status certification unless greater efforts are made to engage marginalised groups in testing and vaccination.

In the past, the effect of health certification schemes to exclude people has been the subject of protest and resistance. And in relation to the current scheme in Israel, where certification has been enforced in workplaces, the green pass scheme has led to exclusions and social conflicts.

In the UK policy context, it’s important to consider the different types of activity for which COVID-status certification might be applied:

  • First, it is likely that any certification scheme used for international travel will be less controversial, and may be separate from any system used domestically.
  • Second, while certification for entry to pubs, public transport, shops and even workplaces has been discussed, this is not currently being proposed by the UK government.
  • Third, the one area where there have been calls for, and planning around, the use of certification is the live events industry. The UK Government’s Events Research Programme, which is overseeing research on pilot live events (mostly sport, but with the possibility of music and other events) currently taking place in the UK, is an opportunity for independent scientific evaluation of certification schemes, preferably using principles of open science (e.g., pre-registered protocols, data-sharing). Monitoring such schemes in this way could enable organisers to make modifications in response to possible unintended behavioural outcomes (e.g., reduction in adherence to protective behaviours) – for example, by providing clearer messaging on the protection afforded by vaccination and the need to maintain protective behaviours until more is known about the ability of the vaccine to prevent transmission.

The question of how to prevent discrimination

A limitation of the research covered in our rapid review is that the studies did not examine COVID-status certification specifically for live events. It seems likely that such schemes would be less controversial than certification as applied to everyday activities such as entry to pubs, shops, and workplaces. This was certainly the argument of one events industry lobby group, which found that 84% of those surveyed ‘agreed to additional biosecurity measures when attending an event’.

This evidence of public support for use of certification at live events might be because many are already excluded from attending a football match or the theatre because they don’t have the money to buy a ticket. Plans for certification schemes in the sports and music sectors suggest that these industries think few of their customer base are going to be excluded by a requirement to undergo a lateral flow test or show evidence of vaccination.

Yet the recent call from many in the arts industry for a certification scheme also declared that such a system must not be discriminatory. This statement therefore implies that discrimination is possible in such a system. The question that is not clear to me is how such discrimination could be prevented.

John Drury is a professor of Social Psychology at the University of Sussex