IN the recent past we have been drawn to some discussions regarding the use of immunity passports in the context of COVID-19. The simple reason is that COVID-19 has led to a shutdown of social and economic activities worldwide through lockdowns. As such, some health experts and authorities in some countries are thinking of means of opening up their economies, thus the consideration of issuing out of immunity passports to recovered COVID-19 patients.
What is an immunity passport?
This is also known as “risk-free certificate” or “back to work pass” that would enable individuals to travel or return to work assuming that they are protected against re-infection. The assumption is that if you were infected with SARS-CoV-2, the virus that causes COVID-19, and recover, then you have immunity that will protect you from getting this disease again for some time.
How does it work?
For the immunity passport to be issued, a reliable antibody testing that shows that your body has the antibodies specific to SARS-CoV-2 because you fought off the coronavirus needs to be detected. Usually the development of immunity to a pathogen through natural infection typically takes place over one to two weeks in which white blood cells slow the progress of viruses and sometimes even prevent them from causing symptoms. The body also makes T-cells that recognise and eliminate other cells infected with the virus.
Challenges with immunity passport tests
– First of all, these tests are new and will likely present some challenges in the sense that several of them are at-home test kits, which may rely on the user being able to adhere to instructions correctly.
– The quality of the at-home test kits is also being questioned as it is thought to be unreliable.
– Another thing is that no one knows if people who were asymptomatic to COVID-19 will have enough antibodies in their bloodstream to pass the antibody testing.
– How long this immunity will last is another unknown area, although studies done so far show that the average length of immunity for SARS appears to be about two years. Will this be the same for COVID-19? No one knows for sure.
– It is also said that these tests need to accurately distinguish between past infections from SARS-CoV-2 and those caused by the other known set of six human coronaviruses. People infected by any one of these viruses may also produce antibodies that cross-react with antibodies produced in response to SARS-CoV-2 infection.
– The other issue is that there have been reports of people who have recovered but continue to test positive again after some time. Zambia has two of this type. How will these be handled?
The issuance of immunity passports still remains a huge challenge because something like this has never been done before as the world has never had a pandemic of this scale and level of shutdown. Maybe it may be too soon to consider issuing immunity passports.
The World Health Organisation (WHO) reports that it has continued to review the evidence on antibody responses to SARS-CoV-2 infection. WHO reports that “most of these studies show that people who have recovered from COVID-19 infection have antibodies to the virus”. Unfortunately, some of these people show very low levels of neutralising antibodies in their blood. As of April 24, 2020, it was reported that “no study had evaluated whether the presence of antibodies to SARS-CoV-2 adequately confers immunity to subsequent infection by this virus in humans”.
WHO fears that the use of such passports may therefore heighten the risks of continued transmission. However, as new evidence becomes available, the world will be updated.
The author is a public health consultant and an M&E specialist currently working for the Ministry of Health – Zambia as senior planner.