COVID-19 antibody testing and ‘immunity certification’

SARS-CoV-2, the virus that causes COVID-19 disease, is a novel pathogen against which human populations have no specific, pre-existing immunity. The virus may be passed on before symptoms appear and many infected people clear the infection without showing any symptoms. Certain groups, particularly older people, are statistically more likely to experience severe forms of the disease.

Until effective vaccines or treatments become widely available most states have sought to protect public health through non-pharmaceutical interventions, such as use of personal protective equipment, the closure of businesses, restrictions on public movement and so-called ‘social distancing’. This has required exceptional state action and has had significant impacts on businesses, livelihoods and relationships.

People who have recovered from COVID-19 may have acquired a degree of protection and be less able to transmit the virus to others. It has been suggested that, if these people could be distinguished from others who are more susceptible, the general restrictions in force to protect public health need not (and should not) be applied to them. Such an approach would allow an increase in social and economic activity, at least for a section of the population. For this to be feasible, at least four things are required:

• an understanding of what factors correlate with increased protection against the virus (for example, the presence of specific antibodies in the circulation),
  
• a reliable means of detecting these factors in individuals (for example, a validated biomedical test),
• a secure means of authenticating information about these factors relating to particular individual (for example, a fraud-resistant form of certification), and
• the acceptability (or acceptance) of a policy that applies different restrictions to different groups of people based on these results.

A public policy that permits citizens to be treated differently in such a way is likely to be guided by the judgement that it is safe to restore liberties to those at low risk of infection/ transmission while maintaining no greater restrictions on those who remain susceptible than are proportionate to the public health risk. It is far from assured, however, that the benefits of restoring liberties to some will not come at a cost to the interests of others.