Are “vaccine passports” a good idea? Well, much depends on what is meant by the term, for it is used to refer to a host of very different things.
First, it can refer to many different activities, from the ability to travel abroad to the ability to go to work.
Second, it can refer to many different people, from the population at large to those in specific occupations.
Third, it can refer to many different times, from early in the vaccine rollout to the point where the entire population has been offered their two jabs.
Public support for vaccine passports varies greatly as a function of these various factors. By and large, survey evidence from a range of countries, including the UK, suggests that people are more favourable to the idea to the extent that it relates to activities seen as optional (rather than integral) to everyday life such as international travel, to those (such as health staff) who work with vulnerable populations, and to a future date when the vaccine rollout is completed. [1-3] That is why Boris Johnson’s specific suggestion that pub landlords might demand evidence of vaccination before allowing entry has proved so controversial even amongst his own allies, and indeed has led to some rapid backtracking by the prime minister. [4-6]
There are many reasons to oppose “vaccine passports” for everyday social activities like going to the pub. They raise a whole series of technical, ethical, and legal questions about how certification would work, how privacy could be maintained, how the scheme would be implemented and enforced, how fraud could be avoided. [7-10]
They also raise a whole series of social and political questions notably about social inequalities, social division, and social conflict. Indeed, this is a pandemic of inequality where, on almost every measure, including vaccine take-up, there are significant differences between the privileged and the deprived, the secure and the vulnerable. This is certainly true of Israel, whose green pass scheme is seemingly the model for Johnson’s comments. Here, the Israeli Arab population constitute 39% of those who have had no vaccination, though they only constitute 21% of the population. [11-12] Indeed, in some Arab villages the vaccination rate is little over 1%. It is equally true of the UK, as the latest ONS figures reveal. Among the over 70s, 91.3% of white British people have had a first dose, higher than any other ethnic group. Among Black Africans, the figure falls as low as 58.8%. 
While the reasons for these discrepancies are complex (certainly, in Israel as in the UK, the vaccine is freely available to all), the danger is that adding vaccine passports to such existing vaccine inequities results in a form of vaccine apartheid. Members of marginalised groups, who are less likely to be vaccinated, are thereby more likely to be excluded from participation in everyday social life. If such social division is not serious enough on its own, the enforcement of this exclusion—through demanding that people produce their vaccine passports to be in public spaces or places that people feel they have a right to enter (not only pubs, but also shops, live events, and workplaces) runs the danger of creating flashpoints of collective conflict. 
But at this point in the argument, those supporting vaccine passports can produce a strong trump card. In addition to generating economic and social activity, a key justification for the policy is to give those who might otherwise be reluctant an incentive to get vaccinated. This becomes especially important as vaccine roll out begins to include younger age groups who suffer less from covid-19 infections and therefore have less reason to get the vaccine in order to protect their health. The ability to go to the pub is designed precisely in order to provide just such a reason.  In other words, it is argued that vaccine passports help increase take-up and ensure that no-one needs to be left out.
At first glance, it is a plausible position. So, it is important to consider the evidence on vaccine passports and vaccine take up. One US study from September 2020 suggests that incentives could have an effect—although these are incentives like visiting a care home, travel, attending religious gatherings, going to work and school rather than social activities like going to the pub.  Another small Israeli survey found that 31% of respondents said that the green pass would persuade them to get vaccinated while 41% said it would not. 
These are modest findings, but there is an important caveat even so. The data are based on general population samples, but the critical issue is not the effect that vaccine passports might have on people in general. If one wants to increase take-up, it is the effect on those individuals and communities who harbour doubts about vaccination which matters.
Based on hard experience, such communities (ethnic minorities in particular) have reason to question whether medical and governmental authorities treat their needs as a priority and this historical distrust provides a framework for interpreting contemporary pandemic policies.  Members of these communities are more attuned to the possibility that such policies (including vaccination) are something done to them rather than done for them by authorities who are not of them but against them. Moreover, there are plenty of anti-vaxxers aiming to promote this view by arguing that covid measures are not a matter of public health, but of social control by a hostile elite.  The reality, and even the rumour, of vaccine passports for core activities serves to give substance to these fears and to give traction to the anti-vaxxers. Passports can be seen as confirming the perception that vaccination is a measure of compulsion imposed upon the community. And once people begin to regard vaccines as compulsory then the evidence suggests that this produces anger and reduces willingness to get vaccinated. 
All in all, there are reasons to conclude that vaccine passports for basic activities may actually undermine vaccine rollout by disincentivising the very populations who most need incentivising. Closer inspection of the Israeli “green pass” scheme serves to reinforce this message. The evidence for passes increasing vaccination uptake is weak, while suspicions of compulsion and reports of people barred from workplaces for not being vaccinated have “resulted in antagonism and increased distrust among individuals who were already concerned about infringement on citizens’ rights”.  By contrast, what has proved successful in Israel are basic measures of community engagement: involving trusted community leaders, taking mobile vaccination units into communities, bringing along medical experts who can answer any questions, and providing food and drink to those who attend, has proved successful in Israel. 
To conclude: there are many good reasons to reject any passport scheme which makes everyday social participation dependent on vaccination. There are arguments on the grounds of liberties, of equalities, and of practicalities. However, even some of the grounds used to support them (i.e. vaccine take-up) may be another reason to oppose them. At a point in the pandemic where increased engagement is critical, both in order to overcome doubts about vaccination, and to enhance the pandemic response more generally, the mere possibility of vaccine passports threatens to alienate marginalised communities still further. [23,24]
So, let’s stop discussing the use of vaccine passports as a criterion for basic social and economic participation. This is an idea with few redeeming features and even talking about introducing them may be enough to do damage.
Stephen Reicher, School of Psychology and Neuroscience, University of St. Andrews.
John Drury, School of Psychology, University of Sussex.
Competing interests: SR participates in SPI-B, in the advisory group to the Scottish chief medical officer, and in Independent SAGE. JD participates in SPI-B and Independent SAGE. Both are writing in a personal capacity.
Funding: This piece is linked to a UKRI grant: ‘Facilitating the public response to covid-19 by harnessing group processes’ Ref:ES/V005383/1.