Could Getting COVID-19 Now Protect You From Getting It Again?

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Could getting COVID-19 now protect you from getting it again? Such a great question, with enormous ramifications for both public policy and vaccine development. Alas, the answer is: we don’t know.

There are other coronaviruses that infect humans and cause common colds, and they don’t elicit long term immunity; people can get sick from them and then get reinfected again within a year. But the SARS virus that circulated in 2003 generates immunity that lasts for much longer. We don’t yet know where in this temporal spectrum this new virus will fall.

The current SARS-CoV-2 endemic started in Wuhan, China, in  mid-November. Already by February, there were reports circulating that some Chinese patients who had been released from the hospital because (it seemed) their infections had passed were testing positive again. This was concerning, because if people could be reinfected, that could limit the utility of any vaccines in development. 

Chinese scientists have just reported that when they infected monkeys with the SARS-CoV-2 virus, watched the monkeys sicken and recover, and then exposed the monkeys to more virus, the second infection didn’t take. The reinfected monkeys looked just like the ones who had recovered and never been re-exposed to the virus. The scientists claim that the patients in China who seemed to be reinfected  were not; rather, they had never actually cleared their initial infection, and the tests that showed they did were just not sensitive enough to pick up their recurring initial infection.

This could be good news, but there are A LOT of caveats attached to this study. Number one: it was done in monkeys, which respond differently to SARS-CoV-2 than we do. Number two: it was done in only four monkeys, only two of whom had the virus reintroduced to them. It’s hard to conclude anything from two monkeys. Even two hundred would be too small of a sample size to be significant. And number three: the monkeys got their second viral challenge only twenty-eight days after their first infection. Even if two monkeys could provide a proof-of-concept, the demonstrated month of immunity will not do human society much good. 

Luckily, pregnant women and fetuses do not seem to be especially at risk of COVID-19. From the very little information we have, pregnant women who are infected do not seem to have more extreme cases, to pass the infection to their babies after giving birth, or even to pass the infection to newborns via breast milk. But as of now, the CDC is recommending that infected women who give birth stay separated from their newborns for two weeks. And of course pregnant women should still take the same precautionary measures as everyone else right now–hand washing, social distancing–to keep themselves healthy and safe.

Diana Gitig
Dr. Diana Gitig has a Ph.D. in cell biology and genetics from Cornell University, and has been writing about issues in biology – from molecular biology to cancer to immunology to neuroscience to nutrition to agriculture - for the past fifteen years. She has three teenaged children.

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