Medical employees wear protection gear at a newly opened drive-in corona special test center for Dresden public service employees such as police officers, nurses and firefighters, amid the spread of the coronavirus (Covid-19) in Dresden, eastern Germany, April 15, 2020.

Trapped between the competing urgencies of saving lives from Covid-19 and avoiding economic calamity, some government officials have mooted “immunity passports” as a way through the impasse. But experts told FRANCE 24 that the necessary antibody testing is not reliable enough – and even if the scheme were feasible, it could create a dangerous incentive for some to acquire the virus in order to qualify for the passport.

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The global tally of confirmed coronavirus cases surpassed 2 million on Wednesday – a day after researchers at the Harvard School of Public Health warned that the US may need to keep some social distancing measures until 2022, while the IMF predicted that, thanks to “the Great Lockdown”, the world will suffer the worst recession since the Great Depression.

Anxious about both the unfolding economic disaster and the risk of Covid-19 resurging if lockdowns are reversed prematurely, some officials in hard-hit countries have suggested that a system of immunity passports could be a route out of the coronavirus crisis – for some at least. The idea is that people who have already had the disease and thereby gained immunity could be given permits to live their lives mostly like they did before the pandemic.

Shortly after emerging from self-isolation after testing positive for Covid-19, the UK’s Health Secretary Matt Hancock announced in early April that the British government was considering an “immunity certificate” system to allow those who qualify to “get back as much as possible to normal life”.

Paris Mayor Anne Hidalgo has also given the idea her backing – putting it in a list of proposals for returning to business as usual in the City of Lights that she sent to the French government. On the other side of the Atlantic, Anthony Fauci, the director of the US National Institute of Allergy and Infectious Diseases, told CNN that immunity passports are “being discussed” in the Trump administration. “It might actually have some merit under some circumstances,” he added.

Antibody tests ‘not sufficiently accurate’

Immunity passports would require tests for antibodies specific to Covid-19, which would be different from those used to discern whether or not people currently have the virus. The problem is that, as things stand, these tests “are not sufficiently accurate for individual immunity passports”, which means that “we are still a long way off it being useful to test individuals with these methods”, said Claire Standley, an assistant professor at Georgetown University’s Center for Global Health Science and Security.

A major reason why such tests look likely to be ineffective, Standley explained, is that they do not seem specific enough to avoid mistaking a similar virus for Covid-19: “There may be cross-reactivity between the antibodies for SARS-CoV-2 [Covid-19] and other circulating coronaviruses – including those that cause common colds – meaning a positive result might not indicate past exposure to SARS-CoV-2 but maybe another coronavirus instead.”

As well as flagging up people who have recovered from ailments that merely seem similar to Covid-19, Standley said these tests also have a problem in failing to detect some people who have experienced a minor form of the virus: “High false negative rates (lack of sensitivity) of the test mean that those currently available are not recommended for patient-level clinical diagnosis; unless the sensitivity improves, these tests may also not be effective in identifying people who have recovered from mild cases of Covid-19, and thus may have lower levels of antibodies in their blood.”

Immunity for less than one year?

Issues with the accuracy of testing equipment may be solved through rapid technological advances as the world’s scientists focus their energy and resources on tackling the coronavirus pandemic. However, one potentially intractable problem with immunity passports is that immunity might not last terribly long.

“At this point, the virus has been widely circulating in Europe and North America only for a couple of months, and so that is all the information we have – we will know in a year if immunity lasts a year; we will know in two years if immunity lasts two years,” noted Abram Wagner, an assistant professor of epidemiology at the University of Michigan. “From past research into other coronaviruses, immunity was not long lasting, and I would not be surprised if, for most people, immunity lasted less than one year.”

In addition to these scientific hindrances standing in the way of immunity passports, there are worries about the social implications: “I suspect many people will be resentful if others were able to return to work and make money because they had an immunity passport,” Wagner put it.

“I have grave concerns about how these types of schemes could be implemented equitably and fairly, even assuming a reliable antibody test were available, and more known about the length of immunity and how protective it is,” Standley added.

In particular, she said, immunity passports threaten to accentuate inequality between the haves and have-nots, which lockdowns have already intensified: “If the tests need to be purchased, this could further exacerbate disparities between those who can afford the tests (and who may already have been able to work from home/maintain an income during lockdown) versus those who cannot, and thus would be further barred from re-entering the workforce.”

Another unsettling point Standley raised is that immunity passports could create a perverse incentive to contract the coronavirus: “In an effort to return to work, or allow their children back to school, will the promise of an immunity passport make people behave less responsibly, and risk infection, in order to end up with a positive antibody test?”

In this way, an idea touted as a way of giving people their lives back could disadvantage those who have acted most virtuously, Standley warned: “The scheme would potentially punish those citizens who have behaved responsibly and tried their best to reduce their own risk of exposure and that of transmission within their communities.”

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