A 33-year-old man has contracted COVID-19 after recovering from the disease earlier this year in what was believed to be the first case of reinfection in the world, researchers announced Monday.
Investigators from the University of Hong Kong said the man tested positive again at the airport after returning from a trip to Spain this month, the Japan Times reported.
“An apparently young and healthy patient had a second case of COVID-19 infection that was diagnosed 4.5 months after the first episode,” researchers said, according to the New York Times.
Using sequence analysis, researchers determine that his strain of the virus this summer turned out to be spreading across Europe.
“Our results prove that his second infection is caused by a new virus he recently contracted instead of by prolonged viral contamination,” said Dr. Kelvin Kai-Wang To, a clinical microbiologist at the university.
Doctors have previously reported cases of presumed reinfection, but this case is the first to be confirmed through scientific tests.
The evidence could have important implications for how experts understand coronavirus antibodies, researchers said.
“Before this report, many believe that recovered COVID-19 patients have immunity to re-infection, but there is evidence that some patients have a declining antibody level after a few months,” the researchers wrote in a statement, according to Japan Times.
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