Some Recovered Coronavirus Patients Testing Positive Again

Some people who have contracted COVID-19 and recovered from it are contracting it again, concerning public health officials. On Friday, a report from South Korea claimed that 91 patients who had been cleared of coronavirus had tested positive again. According to a report by The Hill, the World Health Organization is investigating.

Officials say that the patients in South Korea may have had their coronavirus "reactivated" rather than having been re-infected by it. Still, the WHO mandates that patients get at least two negative COVID-19 tests before they are discharged from the hospital. That was the case for these 91 patients, who were all preparing to leave the hospital when they suddenly became ill again.

"We are aware of these reports of individuals who have tested negative for COVID-19 using PCR (polymerase chain reaction) testing and then after some days testing positive again," a WHO spokesperson said. "We are closely liaising with our clinical experts and working hard to get more information on those individual cases. It is important to make sure that when samples are collected for testing on suspected patients, procedures are followed properly."

Experts also pointed out that as many as 14 days can pass between the contraction of the coronavirus and the start of symptoms, then another 14 between the onset and the clinical recovery from the virus. "We are aware that some patients are PCR positive after they clinically recover, but we need systematic collection of samples from recovered patients to better understand how long they shed live virus," the WHO said.

So far, experts are not clear on how long survivors of COVID-19 may retain immunity to the virus — if at all. On Monday, epidemiologist Marc Lipstitch wrote an op-ed for The New York Times detailing the apparently slim body of evidence about immunity to this virus. He laid out the available data on various forms of coronavirus, as well as SARS and MERS. Survivors of these three illnesses do not get long-term immunity from the experience.

"These studies form the basis for an educated guess at what might happen with COVID-19 patients," Lipstitch explained. Based on what we know now, people who have survived COVID-19 may have a slightly stronger immune response to the virus if they are exposed again, but those defenses may last about a year at most.

"I can only hope that this article will seem out of date very shortly — as much more is soon discovered about the coronavirus than is known right now," Lipstitch concluded. For the latest information on the coronavirus pandemic, visit the CDC's website.