(Bloomberg) – The first study to investigate the case of a person in the United States who contracted Covid-19 twice found that reinfection can occur quickly and the second bout of the disease can be more severe.
The research, published in the Lancet medical journal, looked at 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. He tested negative twice in the middle, which means he is unlikely to have suffered a single prolonged infection.
The results come when US President Donald Trump claims he is immune to the virus after a single meeting. Any new resistance discovery may also have implications for a vaccine as drug makers race towards the finish line.
The degree of protective immunity after a Covid-19 infection is one of the great unknowns of the pandemic.
A handful of cases of reinfection have been recorded so far since the outbreak began at the end of last year. A patient in Ecuador also suffered a worse bout of disease the second time and an elderly woman in the Netherlands died after testing positive a second time. It is also possible that people without symptoms can be infected multiple times without knowing it.
The Nevada man tested positive for the virus for the first time in mid-April after experiencing headaches, coughs, nausea and diarrhea. He had no underlying conditions that could have made his illness worse. He isolated and recovered by the end of the month.
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In late May, however, the man consulted at an urgent care center with fever and dizziness in addition to the symptoms he had experienced the previous month. Five days later he was hospitalized for shortness of breath and given oxygen before testing positive for Covid-19 again.
The scientists sequenced the genomes of the patient’s virus samples and found significant differences, suggesting that the man had been infected with two distinct 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 the virus the second time around, that the version he encountered was more virulent, or even that the presence of antibodies from the first infection was the cause of a torsion seen with another coronavirus. It is also possible, but unlikely, that there has been a continuing infection with some sort of deactivation-reactivation dynamic, 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 results signal that a previous SARS-CoV-2 infection may not necessarily protect against future infections. The possibility of reinfection could have significant implications for our understanding of Covid-19 immunity, especially in the absence of an effective vaccine. “
(Updates with the death of the Dutch woman in the fifth paragraph)
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