You can catch covid-19 twice, but the second bout is likely to be mild

Back in August 2020, a worrying report came in from Reno, Nevada. A 25-year-old man who had recovered from covid-19 in April had fallen ill with it again, and this time his symptoms were worse. He had tested negative for the virus in between bouts, so had been infected twice. Other reports of reinfection were also circulating at the time, raising fears that infections don’t lead to long-lasting immunity. Nine months on, however, those fears have receded...