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Can people who have already tested positive for COVID-19 and recovered be infected again?
And do the COVID-19 antibodies they carry prevent them from infecting others?
The answers may determine how fast countries can restart their economies after business and travel were largely shut down to combat the pandemic in recent months.
Health officials in South Korea said last week that 91 people who have been re-tested for the coronavirus after being released from quarantine have again tested positive.
Wall Street analysts have covered anecdotal reports of reinfections, which raise other concerns for them about the usefulness of a vaccine and the quality of testing. An unnamed infectious-disease expert told SVB Leerink analysts in April that “reinfection to the same coronavirus is likely, and the immunity may be short-lived.”
Dr. David Perlin, chief scientific officer of Hackensack Meridian Health’s Center for Discovery and Innovation, said the reappearance of the virus in recovered patients may indicate that it can live in the gastrointestinal tract in some cases.
“There are clearly a subset of individuals who had a confirmed infection, recovered, are clinically well and tested virus negative, but now are showing up weeks later as virus positive,” he told MarketWatch via email. “It is not clear how infectious the new virus particles remain. From an infection control perspective, it is a serious concern.”
There is no scientific consensus yet on whether reinfection with the virus is possible among those who have already recovered.
Dr. Deborah Birx, the White House coronavirus response coordinator, said April 1 that if you have COVID-19 antibodies, “you’re safe from reinfection 99.9% of the time,” while officials at the World Health Organization have cited the relative newness of the virus and the lack of peer-reviewed scientific research for the lack of clarity. “With regards to a recovery and then reinfection, I believe we do not have the answers to that,” Dr. Mike Ryan, executive director of WHO’s health emergencies program, said Monday at a news conference. “That is an unknown.”
Early clinical data published by researchers in Shanghai found that the level of antibodies in 175 recovered COVID-19 patients varied. This data hasn’t been peer-reviewed or part of a formal clinical trial. This may indicate that a recovered individual’s immunity may have to do with the severity of their disease — not all patients are hospitalized, and not all patients present symptoms, for example. Bernstein analysts have said that in instances of a second positive test, whether that’s due to a reinfection or an inaccurate first test, those patients “were asymptomatic [the] second time around.”
“Right now the information is mixed,” Dr. Maria Van Kerkhove, WHO’s COVID-19 technical lead, said Monday during the news conference. “We need much more information from recovered patients. There’s more than 300,000 people globally who have recovered, and we really need to better understand what that antibody response is.”
At least 464,000 people worldwide have recovered from the virus, including about 44,000 people in the U.S., according to data aggregated by Johns Hopkins University.
A number of companies and public health organizations are developing serological tests that they hope can be used to identify who has COVID-19 antibodies to help decide whether those individuals can begin to move more freely in their communities.
Quest Diagnostics Inc. DGX, +4.59% is the latest lab testing company to announce plans to develop antibody tests. Some officials and researchers believe this would allow some people to return to work and loosen the social-distancing restrictions that have hampered the economy in the U.S.
“This would be a game changer in restarting parts of the economy more quickly and safely,” Dr. Harvey Fineberg, a professor in the Harvard T.H. Chan School of Public Health, wrote in the New England Journal of Medicine on April 1.
Beaumont Health, a hospital system in Michigan, said Monday that it is studying whether antibodies in people who have recovered from COVID-19 offer protection to those individuals afterward. The serological testing study plans to voluntarily ask its 38,000 employees who have not reported symptoms to be tested for COVID-19 antibodies. The results are expected to inform the hospital system’s return-to-work process and may also set protocols for which members of the public will get a vaccine first, it said.
See:St. Louis Fed’s Bullard pitches universal daily COVID-19 testing to help restore economy’s health
German researchers have proposed the idea of “immunity certificates,” which would allow those individuals who have antibodies to step back into their normal lives. The Helmholtz Centre for Infection Research plans to conduct a study of at least 100,000 people who will regularly be tested for antibodies.
