Serological tests detect antibodies to coronavirus in the human body, but they cannot show whether it is protected from re-infection, the World Health Organization said. Some countries plan to do this when quitting quarantine.
Representatives of the World Health Organization pointed out at a briefing in Geneva on April 17 that there was no evidence that antibody tests could show the presence of immunity to coronavirus. The video of the briefing is published on the organization’s YouTube channel.
Maria Van Kerchove, Technical Director of the WHO Health Emergencies Program, noted that many countries want to use serological tests (antibody tests) to determine immunity to coronavirus, but she cautioned against this method.
“Now we have no evidence that a serological test can show that a person is immune or protected from re-infection. These tests can measure the level of antibodies in the human body a week or two after infection,” said Van Kerchove and emphasized that “the presence of antibodies doesn’t mean that someone is immune. “
Her colleague Michael Ryan, Executive Director of the WHO Health Emergencies Program, pointed to the ethical side of the issue.
“There are serious ethical issues associated with using this approach, and we need to be very careful about this. We need to examine the degree of protection that antibodies can give. No one is sure if a person with antibodies is completely protected from reinfection. Moreover, some tests have problems with sensitivity, they can give a false negative result. Someone who considers himself to be seropositive and protected, in fact, in some situation may be infected, “Ryan said.
WHO has promised to release an updated guide on this issue soon.
For the detection of SARS-CoV-2 coronavirus in the human body, polymerase chain reaction testing (smears are taken from the mucous membrane of the nasopharynx and oropharynx) is widely used throughout the world. Serological testing analyzes blood serum, The Conversation noted. These tests are not looking for the virus itself, but for antibodies that the body’s immune system produces to fight infection. Because antibodies do not appear immediately, serological tests are ineffective in the early stages of infection. One of the benefits of serological testing is the ability to determine the infection of people who have been asymptomatic, and therefore were not taken into account in general statistics, The Conversation said.
Some countries have announced plans to conduct serological testing during quarantine exits. For example, the U.S. Food and Drug Administration reported this. “The results of these tests can help determine who was infected and developed antibodies that can protect against infection in the future, as well as identify those who are still at risk,” the organization said in a statement on April 18. The Ministry of Health of Ukraine also announced plans to test for antibodies.
The outbreak of COVID-19 infection began in December 2019 in Wuhan, China. On March 11, 2020, WHO announced the spread of coronavirus in a pandemic. According to the American Johns Hopkins University, the number of confirmed cases of coronavirus infection in the world exceeded 2.4 million, more than 635 thousand people recovered, and 166 thousand died.
This month, South Korea announced the re-infection of people who have been ill COVID-19. The country is investigating the causes of the incident, but does not rule out problems with the tests.