A 25-year-old Nevada man was found to have been infected twice with COVID-19 earlier this year, scientists confirmed. It is the first confirmed case of coronavirus reinfection in the U.S. Four other cases have been found worldwide.
NPR was the first to report the case of reinfection.
The case throws a wrench in prior held beliefs by some, and recently suggested by President Donald Trump, that once a person has overcome the virus they are "effectively immune."
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The two infections in the patient happened around six weeks apart, according to a case study in the medical journal The Lancet published Monday. The patient first tested positive for the virus in April, recovered and then tested negative again in May.
"Our findings signal that a previous infection may not necessarily protect against future infection," said Dr Mark Pandori of the University of Nevada.
"The possibility of reinfections could have significant implications for our understanding of COVID-19 immunity."
Pandori said that even if someone has fully recovered from the virus they should continue following social distancing guidelines including face masks and washing their hands.