Coronavirus: Immunity passports “may increase spread of virus”

Governments should not issue so-called “immunity passports” or “risk-free certificates” as a way to ease blockages, says the World Health Organization (WHO).

He said there was “no evidence” that people who had developed antibodies after recovering from the virus were protected against a second infection.

Such a move could increase transmission of the virus, he warned.

People who assumed they were immune could stop taking precautions, he said.

Some governments have considered allowing people who have recovered to travel or return to work.

• Does Sweden have its correct coronavirus science?
• Double warning about virus antibody tests

Restrictions on movements to stop the spread of the virus have paralyzed economies around the world.

More than 2.8 million cases of the virus have been confirmed worldwide and almost 200,000 people have died.

What did the WHO say?

“There is currently no evidence that people who have recovered from Covid-19 and have antibodies are protected from a second infection,” the WHO said in an information note.

Most of the studies done so far showed that people who had recovered from an infection had antibodies in their blood, but some of these people had very low levels of antibodies.

This suggested that another part of the body’s immune response, T cells, which kill infected cells, may also be “critical” for recovery.

As of Friday, no study had evaluated whether the presence of antibodies to the virus conferred immunity to subsequent virus infection in humans, the WHO said.

“At this point in the pandemic, there is insufficient evidence on the effectiveness of antibody-mediated immunity to ensure the accuracy of a ‘immunity passport’ or ‘risk-free certificate,'” he said.

The organization also said that laboratory tests to detect antibodies needed additional validation to determine their accuracy and also to distinguish between previous infection with the SARS-CoV-2 virus, which has caused the pandemic, and the other six known coronaviruses in circulation.

Passports too risky, for now

Analysis of Rachel Schraer, BBC health reporter

WHO’s guidance is based on evidence from researchers around the world. But it could well change as we quickly learn more about this virus.

There is currently no evidence to suggest that having the virus once protects you from contracting it again. Therefore, the idea of ​​an “immunity passport,” allowing people who test positive for antibodies to have fewer restrictions, would be very risky.

Many countries, including Germany, Italy, and the United Kingdom, are beginning to test samples from their populations for antibodies. In the UK, 25,000 people will be tested every month for the next year, both to detect antibodies and to check if they currently have the virus.

This could provide more information on whether (and for how long) the disease confers immunity to those who have recovered. And that would give us a clearer idea of ​​whether evaluating people and giving them some kind of immunity status might be an option in the future.

Where are ‘immunity passports’ considered?

Last week, Chile said it would begin issuing “health passports” to people who have recovered from the disease.

Once screened for the presence of antibodies that make them immune to the virus, they could join the workforce, authorities said.

In Sweden, which chose to keep large parts of society open, some scientists believe that people can end up with much higher levels of immunity compared to those who live under stricter regulations.

However, Anders Wallensten of the Swedish Public Health Agency told the BBC that not enough was known about immunity yet.

“We will know more as more people are tested for antibodies, but also as more time passes, and if more reports of reinfection are reported, etc.,” he said.

In Belgium, which has one of the highest per capita death rates, but plans to gradually tighten closure restrictions starting May 11, a government adviser told the BBC that he strongly opposed the idea of ​​passports. immunity.

“I hate the fact that we would give people passports, one green or one red, depending on their HIV status,” said virologist Professor Marc Van Ranst, a member of the Belgian government’s Risk Assessment Group and Scientific Committee on Coronavirus. .

“That will lead to counterfeiting, to people who will voluntarily become infected with the virus. This is not a good idea. It is an extremely bad idea.”

Earlier this week, Professor Mala Maini of University College London said that reliable antibody tests were urgently needed to determine how long the antibodies persisted and whether they conferred protection.

“We are still not sure if these antibodies indicate protective immunity against SARS-CoV-2, but preliminary data suggests that they may be a reasonable proxy for this, so they are considered to report blocking release, etc.” said.