Given the rate at which cured people are getting re-infected with coronavirus, and the rate at which some health authorities favor antibody tests, the World Health Organization (WHO) has warned that antibody tests are not a guarantee that someone has developed enough immunity and cannot be re-infected with COVID-19 again.
Dr. Maria Van Kerkhove, head of WHO’s emerging diseases and zoonosis unit, said it is possible for antibody tests to reveal the level of antibodies or serological presence in the body, but that does not indicate that an individual is immune to getting re-infected.
She stated that research has shown that many people do not have any antibodies after getting cured of coronavirus and that some people still get re-infected even with high antibodies following initial cure. She added that most of the serological tests have done is to prove whether an individual had had coronavirus in the past and is recovered or asymptomatic.
According to the WHO official, it is possible for a person who has been cured of COVID-19 to still infect others or be re-infected.
According to data from Johns Hopkins University, more than 2.1 million people have been infected with COVID-19 with 560,000 of these already cured and discharged from hospitals. In the United States, over 671,000 are infected and over 200,000 in the United Kingdom. US President Donald Trump has agreed that people with the appropriate level of antibodies can be allowed to return to work as the country begins to relax its coronavirus regulations.
“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,” Dr. Kerkhove said. “Right now, we have no evidence that the use of a serological test can show that an individual is immune or protected from reinfection.”
Dr. Mike Ryan, executive director of WHO’s emergencies program, said while scientists are not certain of the amount of antibodies required for immunity against coronavirus, many antibody tests in the market have been known to give false-negative results.
Professor John Newton in the UK warned members of the public to desist from buying unapproved antibody tests not outrightly endorsed by the government. He said health authorities across the UK are working rapidly to develop a valid serology test that measures levels of antibodies in blood plasma.
“Until then, please don’t buy or take any unproven tests,” he said. “They may not be reliable for your intended use; they may give a false reading and put you, your family or others at risk. As soon as we have found a test that works for this purpose, we will be in a position to roll them out across the country as a back-to-work test.”