That Covid-19 reinfection in Hong Kong was followed by similar reports in Belgium and the Netherlands. It was announced today that a 27-year-old woman in Karnataka, India also tested positive for the disease a second time (though the government is still seeking confirmation), and now researchers in Nevada are also reporting a "likely" case of reinfection.
What caught experts' attention about the case of the 25-year-old Reno, Nevada man was not that he appears to have contracted SARS-CoV-2 (the name of the virus that causes Covid-19) a second time. Rather, it's that his second bout was more serious than his first. Immunologists had expected that if the immune response generated after an initial infection could not prevent a second case, then it should at least stave off more severe illness. That's what occurred with the first known reinfection case, in a 33-year-old Hong Kong man.
Still, despite what happened to the man in Nevada, researchers are stressing this is not a sky-is-falling situation or one that should result in firm conclusions. They always presumed people would become vulnerable to Covid-19 again some time after recovering from an initial case, based on how our immune systems respond to other respiratory viruses, including other coronaviruses. It's possible that these early cases of reinfection are outliers and have features that won't apply to the tens of millions of other people who have already shaken off Covid-19. "There are millions and millions of cases," said Michael Mina, an epidemiologist at Harvard's T.H. Chan School of Public Health. The real question that should get the most focus, Mina said, is, "What happens to most people...?"
Researchers are finding that, generally, people who get Covid-19 develop a healthy immune response replete with both antibodies (molecules that can block pathogens from infecting cells) and T cells (which help wipe out the virus). This is what happens after other viral infections.
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