The World Health Organization has warned governments against issuing “immunity passports” to allow people who show antibodies for coronavirus to return to work.
As leaders across the world turn their focus to reopening their economies after weeks of social restrictions designed to contain the pandemic, many have been hoping to deploy some form of certificate system allowing people deemed immune to travel and work.
But in a scientific brief published on Friday evening, the WHO cautioned against such plans, citing a lack of proof that anyone could be definitively labelled immune from the deadly virus.
“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.
Chile last week became the first country to announce plans to give “health passports” to recovered Covid-19 patients, allowing them to go back to work, Reuters reported.
Germany and the UK have also considered taking a similar approach to help ease the strains on economies suffering their sharpest contractions in decades.
However the WHO said there is not yet enough evidence to guarantee that such measures would work, and that there are no studies on whether the presence of antibodies indicates immunity in humans. It said giving people who have antibodies special rights to travel or work “may therefore increase the risks of continued transmission”.
Reports of 51 patients in South Korea who tested positive after apparently recovering from the virus, as well as cases of reinfections in Japan and China, have raised concerns of scientists’ understanding of Covid-19 immunity.
The WHO also cautioned on the accuracy of antibody tests used to determine immunity and the risk of confusing Covid-19 antibodies with those for other coronaviruses, including four viruses that cause the common cold.
More than 90 commercial antibody tests have been marketed to meet international demand, but many have proved unreliable. Nine different tests evaluated by the UK were all far from meeting the required standards, meaning that none of the 17m ordered by the health department were fit for purpose.
Nonetheless, the UK said this week it plans to test 300,000 people for Covid-19 antibodies over the coming year, while similar schemes are under way in Germany, Finland and New York state.
Developing a reliable antibody test has become a key area of research for some of the world’s biggest pharmaceutical companies.
Roche and Abbott Laboratories are among those hoping to produce millions of accurate test kits in the next couple of months.