Can Tested Positive for COVID-19 After Recovering Get Reinfected With Coronavirus?

Researchers found it was "not uncommon" for people with run-of-the-mill coronaviruses (not the one that causes COVID-19) to have a repeat infection within a year. Of 86 New York City residents infected with those coronaviruses, 12 tested positive for the same bug again.

A big caveat is, the study looked only at the four coronaviruses that are endemic in humans -- the kind that cause nothing worse than cold symptoms.

"They're kind of wimpy," said researcher Jeffrey Shaman, a professor of environmental health sciences at Columbia University Mailman School of Public Health. "People rarely have to go to the doctor for these infections."

So it's hard to know, Shaman said, whether our experiences with endemic coronaviruses will translate to SARS-CoV-2 -- the coronavirus that causes COVID-19.

"It's not the same as these endemic viruses," Shaman said. "But obviously, we can't look at repeat infections with [SARS-CoV-2], because it's new."

In lieu of that, he said, analyzing the patterns of regular coronaviruses -- how often reinfections occur, and in what time frame -- may at least give a sense of what could happen with the new virus.

For the study, Shaman and colleague Marta Galanti looked at data on 191 healthy adults and children living in New York City. Between fall 2016 and spring 2018, the participants regularly gave nasal swab samples and reported on any respiratory symptoms they were having.

Overall, 86 tested positive for a coronavirus infection at some point.

The findings have not, however, been published in a scientific journal yet. According to Shaman, they are undergoing peer review -- the process by which journals decide whether a study is strong enough for publication.

For now, they leave some open questions. It's not clear, for example, that those 12 repeat positives were all actually repeat infections, Shaman said. That's particularly true in cases where the "new" positive result came within weeks of the first, he noted. There, the test may simply have detected the original virus again.

A similar issue is playing out right now with COVID-19, said Dr. Bruce Y. Lee, professor of health policy management at City University of New York Graduate School of Public Health.

There have been some reports of people who'd recovered from the disease testing positive for the virus again.

But, Lee said, those cases seem to reflect issues with the tests -- including detection of "dead fragments" of the virus, rather than a new infection.

However, in the current study, many of the repeat positives happened months after the first infection, Shaman said -- as far out as 48 weeks. It's more likely those would be repeat infections.

Shaman said genetic analyses are being carried out to help confirm which cases are true reinfections.

The study also raises the question of who, exactly, is prone to reinfection -- at least with common coronaviruses. Nine of the 12 repeat positives were in children between the ages of 1 and 9 years. It's not clear why, but Shaman speculated that their immature immune systems could have something to do with it.

Beyond that, all of the study participants lived in densely populated New York City, and some were health care workers. Shaman said the rate and speed of reinfections in the group might not be seen elsewhere.

Around the world, there have been several cases of people recovering from COVID-19 only to later test positive again and appear to have another infection.

Such cases have had doctors and researchers puzzling over whether recovered people continue to be contagious, and if they could get a second infection.

Now, new research published by the Korea Centers for Disease Control and Prevention has found that recovered COVID-19 patients who test positive again aren’t infectious.

The study also found that most patients who recover have neutralizing antibodies — the type of antibody that confers immunity and protects people from getting sick again.

“This study addresses the question of whether patients who have recovered from COVID-19 are still infectious, and which is a question that has been troubling us for some time,” said Dr. Heidi J. Zapata, a Yale Medicine infectious disease doctor. “This study suggests that patients that are recovered are no longer contagious.”

The viral material in re-positive cases isn’t infectious

The Korean study examined 285 patients who tested positive again for the new coronavirus after they recovered from COVID-19, which had been confirmed via a negative test result.

The researchers swabbed the patients and examined the viral material to determine whether it was still actively infectious.

The team was unable to isolate live viral material, indicating that the positive diagnostic tests were picking up dead virus particles.

“[This] may speak for the fact that the virus may be dead or not be fit enough to grow — therefore the virus may not be fit enough to infect a new host,” said Dr. Andres Romero, an infectious disease specialist at Providence Saint John’s Health Center in Santa Monica, California.

The researchers also tested 790 people who’d been in close contact with the “re-positive” patients. Of the 27 who tested positive, no cases appeared to be caused from exposure to someone who appeared to have a reinfection.

The report also found that the vast majority of recovered patients (96 percent) had neutralizing antibodies, indicating that they conferred immunity.

“Whether this is indicative of a completely protective response remains to be proven. If this study holds true, then people who have recovered can get back to work,” Zapata said.

In response to the new findings, South Korea eliminated a policy requiring discharged patients to isolate for 2 weeks.

Need to Practice Caution

While the findings are promising, infectious disease experts say we still need to practice caution.

More research is needed to validate these findings and determine whether they apply to distinct parts of the population, such as those who are immunocompromised.

It’s common for immunocompromised patients — such as those with cancer — to continue testing positive for a virus for longer, since it takes their immune system more time to clear the virus out of their body.

“I don’t think we can be 100 percent certain of whether each recovered person is no longer contagious. Again, this may differ with distinct population groups,” Zapata said.

Physicians are seeing some hospitalized patients testing positive for a month after they were first swabbed for COVID-19. It’s unclear whether these patients still shed infectious virus, according to Zapata.

Everyone’s body mounts a distinct immune response based on their age and overall health. Different individuals will clear the virus out at different speeds, according to Zapata.

Until we have more data and a preventive vaccine, it’s crucial to continue adhering to the safety precautions

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 laid out by the CDC.

“The reality is that moving forward, the best approach will be keeping social/physical distancing, wearing a mask, and frequent hand hygiene in order to control the spread of the virus,” Romero said.

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