The first study to investigate the case of a person in the US who contracted Covid-19 twice found that reinfection can occur quickly and that the second attack of the disease can be more serious.
The research, published in the Lancet medical journal, examined the case of a 25-year-old man living in Nevada who was infected with two different genetic variants of the SARS-CoV-2 virus in less than two months. It tested negative twice in between, meaning it is unlikely that you have suffered from a single long-term infection.
The findings come as US President Donald Trump says he is immune to the virus after just one encounter. Any new findings on resistance may also have implications for a vaccine as drug manufacturers race toward the goal.
The degree of protective immunity after a Covid-19 infection is one of the great unknowns of the pandemic.
So far, there have been five cases of reinfection since the outbreak began late last year. Only one other patient in Ecuador also suffered a worse episode of illness the second time. It is also possible that people without symptoms can become infected multiple times without knowing it.
The Nevada man first tested positive for the virus in mid-April after experiencing a headache, cough, nausea and diarrhea. He had no underlying conditions that could have made his illness worse. It was isolated and improved at the end of the month.
Oxygen is needed
However, in late May, the man consulted an urgent care center with fever and dizziness in addition to symptoms he had experienced the previous month. Five days later, he was hospitalized with shortness of breath and given oxygen before testing positive for Covid-19 once again.
The scientists sequenced the genomes of the patient’s virus samples and found significant differences, suggesting that the man was infected with two different versions of the coronavirus.
The researchers said they couldn’t be sure why the second infection was worse. It is possible that the patient was exposed to a higher dose of virus the second time, that the version he found was more virulent, or even that the presence of antibodies from the first infection was to blame for a twist seen with another coronavirus. It is even possible, but unlikely, that there is an ongoing infection with some kind of inactivation-reactivation dynamics, they wrote.
“There are still a lot of unknowns,” said Mark Pandori, director of the Nevada State Public Health Laboratory and lead author of the study. “Our findings indicate that a previous SARS-CoV-2 infection may not necessarily protect against future infections. The possibility of reinfections could have significant implications for our understanding of Covid-19 immunity, especially in the absence of an effective vaccine.”
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