Some reinfections can be serious A March preprint looked at more than 300,000 Covid-19 patients in the U.S.
VA system. About 9,200 of them tested positive again at least 90 days after their first positive test; 17% of the reinfected patients were hospitalized.
Another 189 cases had a third positive test at least 90 days after their second infection and about 26% of them were hospitalized. “This data suggests to me that it is reasonable to be cautious about reinfection, " says Theodore Iwashyna, an intensive care unit physician at the VA in Ann Arbor, Mich., who is first author of the preliminary study. “There’s a lot of reinfection going on in less than 90 days," says Mark Pandori, director of the Nevada State Public Health Laboratory and an associate professor of pathology at the University of Nevada, Reno.
Dr. Pandori and colleagues have documented two cases that were significantly more severe the second time around. Risk of long Covid after reinfection is unclear Scientists don’t yet know what the risk of long Covid is after a reinfection.