Researchers said a 25-year-old Nevada man may be the first person in the United States to be reinfected with coronavirus, according to a preprint of a study submitted to The Lancet.
Health experts have said reinfections are not unusual and don't want people to worry about the results.
The Nevada man first tested positive for coronavirus in April when he began feeling a sore throat, headache, nausea and cough. After the symptoms disappeared, the man took two more coronavirus tests which both came back negative.
About 48 days went by when the same symptoms began reoccurring more aggressively. He later went to the hospital where he was treated with oxygen.
After examining his RNA sequences of each coronavirus sample, researchers found they were two different strains.
Not much evidence exists about the immune response in patients who've been infected with coronavirus.
Scientists said this means a vaccine may not protect people 100% from coronavirus but acknowledged it was "an established understanding, with influenza regularly demonstrating the challenges of effective vaccine design."
"To scientists, the rare events are important because we learn from them - so we publish them. But unfortunately, academic reports get placed on front page of major media - confusing and scaring many," Michael Mina, an epidemiologist at the Harvard T.H. Chan School of Public Health, tweeted.
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