'No evidence' that coronavirus survivors then have immunity
17 April 2020, 23:08 | Updated: 17 April 2020, 23:19
There is currently "no evidence" that proves coronavirus survivors automatically develop immunity to the disease, the World Health Organisation has said.
Senior epidemiologists at the organisation warned there is no proof that Covid-19 patients cannot be infected again.
Governments across the world have been buying antibody tests in the hope that they would allow coronavirus survivors to return to work after infection.
The UK Government has bought 3.5 million serology tests, which measure antibody levels in blood plasma, despite the tests not definitively proving growing levels of herd immunity.
It is hoped that once people survive coronavirus they will have built up antibodies to the disease and will therefore be safe to return to work.
The tests being bought are similar to the pinprick blood tests used to detect HIV.
However, speaking at a press conference in Geneva, Dr Maria van Kerkhove, an infectious disease epidemiologist for the WHO, said the tests did not prove immunity.
She said: "There are a lot of countries that are suggesting using rapid diagnostic serological tests to be able to capture what they think will be a measure of immunity.
"Right now, we have no evidence that the use of a serological test can show that an individual has immunity or is protected from reinfection."
Dr van Kerkhove added: "These antibody tests will be able to measure that level of seroprevalence - that level of antibodies but that does not mean that somebody with antibodies means that they are immune."
She said that although it was "a good thing" so many tests were being developed, "we need to ensure that they are validated so that we know what they say they attempt to measure they are actually measuring."
Her colleague Dr Michael Ryan said the antibody tests also raised ethical questions.
"There are serious ethical issues around the use of such an approach and we need to address it very carefully, we also need to look at the length of protection that antibodies might give," he said.
"You might have someone who believes they are seropositive (have been infected) and protected in a situation where they may be exposed and in fact they are susceptible to the disease."
Dr Ryan said the tests must be used as part of a responsible and coherent public health policy.
The WHO is expected to give updated guidance measures on coronavirus this weekend.
It comes after US President Donald Trump announced on Tuesday that he would stop all American funding of the organisation.