A Hong Kong man tested positive for coronavirus more than four months after recovering from the disease, becoming the first known case of human reinfection, researchers said Monday.
The 33-year-old man experienced only mild symptoms when he was first infected with COVID-19 in the spring, according to the University of Hong Kong statement obtained by The New York Times.
He tested positive again after returning from a trip to Spain — about 4.5 months after the first infection — according to the paper.
“Our results prove that his second infection is caused by a new virus that he acquired recently rather than prolonged viral shedding,” said Dr. Kelvin Kai-Wang To, a clinical microbiologist at the University of Hong Kong.
Researchers came to this conclusion because they sequenced the virus from both infections and found major differences in two sets.
Dr. Maria Van Kerkhove, an epidemiologist with the World Health Organization, said the public should not be alarmed because this is one case out of more than 23 million confirmed infections worldwide.
“What I think is really important is that we put this into context,” she told reporters at a news conference Monday. “We need to look at something like this on a population level. It’s very important that we document this … But we need to not jump into any conclusions.”
Van Kerkhove assured that those who recover from the virus “do develop an immune response,” even when they experience mild symptoms.
“What is not completely clear yet is how strong that immune response is and for how long that immune response lasts,” she said.
Multiple studies that are still underway are following the same individual over a period of time to learn more about their immune response, according to the WHO.
