It doesn't appear people who have had a confirmed case of COVID-19 can quickly become reinfected with the virus that causes the disease, studies show.
It doesn’t appear people who have had a confirmed case of COVID-19 can quickly become reinfected with the disease, a helpful finding for those worried that even once recovered they may not be safe.
But it remains unknown whether there's any real long-term or even short-term protection for those who've been sick.
Concern was initially raised following reports out of South Korea that some people were becoming reinfected with SARS-CoV-2, the virus that causes COVID-19.
The country’s Centers for Disease Control and Prevention reported more than 300 such cases. South Korea has one of the world’s most extensive COVID-19 testing programs, so its data is considered strong.
South Korean researchers now think they were seeing false positives, where the tests detected old particles of virus in patients no longer causing disease, Reuters reported.
“The South Koreans tried to grow the viruses (from those particles) and they didn’t grow,” said Dr. Ania Wajnberg, an internist at Mount Sinai Hospital in New York City who is medical director of its Serum Antibody Donor Identification program.
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It’s still not known whether having had COVID-19 gives long-term immunity to the virus, but immediate reinfection is now less of a worry.
Wajnberg’s group tested 624 patients who were positive for COVID-19 and recovered. They found all but three were producing antibodies to the virus, indicating their bodies had successfully fought off the infection.
What those antibodies mean in terms of long-term protection remains an unanswered question. But Wajnberg's seen at least one hopeful sign.
“So far, we don’t see any evidence of people being reinfected,” she said.
Confirmation in a large study that almost everyone with a symptomatic infection develops antibodies is promising, said Marc Jenkins, director of the Center for Immunology at the University of Minnesota Medical School.
"But it is still not clear that antibodies are protective and if so, what amount of antibodies are needed for protection," he said.
The differences between diseases can be enormous. Some illnesses, such as measles, give lifelong immunity. For others, such as the common cold, immunity wanes after only a few months.
We can't let our guard down, said Dr. Michael Mina, a professor of epidemiology at Harvard’s Chan School of Public Health.
“It could be two years, so you could get it now and then you could get it in two years and it’s a pretty severe infection,” he said in a call with reporters Friday.
With the SARS-CoV-2 virus having been active among humans for only the past six months, it’s too soon to know.
“It’s just going to take time," Mina said. "We have to follow people over time to see how likely people who’ve been infected are to get a second infection."
SEARCHABLE MAP: Coronavirus death rates and cases for every US county: https://interactives.courier-journal.com/projects/cv19/map/
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