Scientists Confirmed the First Covid-19 Reinfection in the U.S.
A Nevada man who recovered after an April infection tested positive again in May. Here’s what it all means.
An enduring mystery about the coronavirus is how long immunity to the virus lasts, once a person recovers from an infection. While the hope was that immunity would last a long time, it’s becoming increasingly clear that protection from the virus fades and that reinfection is possible. Reports of reinfections in Hong Kong, the Netherlands, Belgium, and Ecuador have already been published during the pandemic. Now, a new case study in The Lancet confirms the first reinfection in the United States.
The paper, which was first published as a preprint at the end of August, follows the medical history of one man, a 25-year-old in Washoe County, Nevada, who tested positive for Covid-19 twice: first in mid-April, then again at the end of May. Two negative tests between his infections confirmed that he’d recovered from the initial illness. He had all the expected symptoms the first time around — sore throat, cough, headache, nausea, and diarrhea — and experienced them again during his second infection, together with low blood oxygen and shortness of breath.
While he recovered in self-isolation during his first infection, he had to be hospitalized the second time around. “The second infection,” the authors of the paper write, “was symptomatically more severe than the first.”
That’s not to say that reinfections are always more severe. The authors, led by bioinformaticist Richard L. Tillett, PhD, of the University of Nevada, say they can only speculate the reasons why the man’s illness was so bad the second time around: It could be that he got a much bigger dose of the coronavirus the second time he was infected. It’s possible that he was reinfected by a more virulent version of the virus (or one that was “more virulent in this patient’s context,” the authors note — a subtle distinction). Or it could be due to a phenomenon called “antibody-dependent enhancement,” in which virus particles latch onto certain antibodies, which makes it easier for them to infect host cells. For now, it’s unclear which is the case.