The World Health Organization has warned that there is no evidence yet that someone who has recovered from Covid-19 is immune to being infected again with the coronavirus.
Dr Maria van Kerkhove, head of WHO’s emerging diseases and zoonoses unit, issued the warning this morning while discussing serological testing of the virus.
Serological, or antibody, tests can indicate whether a person has had Covid-19 in the past and was either asymptomatic or recovered, but Dr van Kerkhove warned they shouldn’t serve as an immunity indicator.
“What the use of these tests will do will measure the level of antibodies. It’s a response that the body has a week or two later after they’ve been infected with this virus,” she said at a news conference at WHO’s Geneva headquarters.
“Right now, we have no evidence that the use of a serological test can show that an individual is immune or protected from reinfection.”
Antibodies are cells created by the body and used by the immune system to neutralise pathogens such as bacteria and viruses but Dr van Kerkhove admitted it’s not yet known whether that response leads to immunity against the coronavirus.
This week, the number of Covid-19 cases surpassed 2,000,000 while recovered cases reached 550,000 and the death toll stood at over 150,000.
Dr Mike Ryan, executive director of WHO’s emergencies programme, said scientists are also still determining the length of protection antibodies might give a person who has been infected with the coronavirus.
“With regards to recovery and then reinfection, I believe we do not have the answers to that. That is an unknown,” Dr Ryan said.
“Nobody is sure whether someone with antibodies is fully protected against having the disease or being exposed again.
“Plus some of the tests have issues with sensitivity,” he added. “They may give a false negative result.”
The WHO also noted the added issue of individual nations differences in testing rates which could alter data significantly.
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