The man, a 25-year-old in Reno, Nevada, was first infected in mid-April. He got sick again in late May, testing positive a second time.
The second COVID infection was more serious than the first, scientists say.
Genetic sequencing revealed the second infection was a slightly different strain, indicating a true reinfection.
The case has been detailed in a document published online.
Reinfections have also been reported in Hong Kong and Europe.
Studies from larger numbers of cases over time are needed before making any definitive conclusions or jumping to conclusions, said Maria van Kerkhove, the World Health Organization’s technical lead on COVID-19, after the announcement by the Hong Kong researchers on Monday, Aug. 24.
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