First Confirmed U.S. Cases of COVID Reinfections

October 12, 2020 – A 25-year-old man from Nevada and a 42-year-old man in Virginia suffered second episodes of COVID-19 about 2 months after testing positive for the first time. Gene tests show that the two men had two slightly different strains of the virus, suggesting that they caught the infection twice.

Researchers say these are the first documented cases of COVID-19 reinfection in the United States. Around two dozen other cases of COVID-19 re-infection have been reported around the world, in Hong Kong, Belgium, the Netherlands, India and Ecuador. A third case in the United States, in a 60-year-old man in Washington, has been reported but has not yet been peer reviewed.

Until now, immunologists weren’t too concerned about these re-infections as most second infections were milder than the first, indicating that the immune system is doing its job and fighting the virus when recognized a second time. .

Unlike most of these cases, however, the men from Reno, NV and Virginia, and a 46-year-old man in Ecuador, had more severe symptoms during their second infections, which could complicate the development and deployment of effective vaccines.

U.S. cases are detailed in new studies published in The Lancet and the newspaper Clinical infectious diseases.

“Coronaviruses are known to re-infect people – the seasonal ones – and so it’s not very surprising to see re-infections occurring with this particular coronavirus,” said Akiko Iwasaki, PhD, an immunobiologist at Yale University who did ‘participated in neither study. “And the fact that there is more serious illness the second time around. It could be one in a million events, we don’t know. We are just becoming aware of cases of re-infection, and they are only a handful of the millions of people infected.

The Nevada man fell ill on March 25. Her symptoms included a sore throat, cough, headache, nausea and diarrhea. A test carried out at a community event held on April 18 confirmed COVID-19. His symptoms gradually improved and he reported feeling better on April 27. He tested negative for the virus twice after he recovered.

About a month later, the man went to an emergency care center with fever, headache, dizziness, cough, nausea and diarrhea. They sent him home. Five days later, he returned to the doctor, this time with difficulty breathing and low oxygen in his blood. They told him to go to the emergency room. He was admitted to hospital on June 5. Chest x-rays showed telltale spots of cloudiness, known as frosted glass opacities, and a nasal swab test confirmed COVID-19. Genetic testing of the two swabs, from April to June, showed key changes in the virus’s genetic instructions on the second test, suggesting it obtained a slightly different strain the second time around.

The man from Virginia – a military healthcare provider – was first infected on the job. He tested positive in late March after having a cough, fever and body aches. He recovered after 10 days and was fine for almost 2 more months. At the end of May, however, a family member contracted COVID-19 and then fell ill again with a fever, cough, difficulty breathing and upset stomach. A chest x-ray confirmed pneumonia. Her symptoms were worse the second time around. Genetic testing of the virus from each of his swabs indicated slight changes, suggesting he was infected twice.

The researchers stress that they cannot be 100% sure these men were. There are other possibilities, including the fact that the virus remained silent in his body for a few weeks and then became active again. The study authors believe this is unlikely because it would mean that the virus is evolving at a much faster rate than what has been seen so far.

They also can’t tell if the severity of the symptoms the men experienced the second time around was related to the virus or their immune system response. Were they sicker because they had received a larger dose of the virus? Was there something about the genetic modifications of the virus that made it more damaging when men caught it again? Or could their first COVID-19 infections somehow have primed their immune system the wrong way, leading to more severe infections the second time around – a phenomenon called amelioration?

Scientists are rushing to try and figure out all of these things and more – what reinfection means and how common it can be. If this happens frequently, it could complicate efforts to achieve a level of community protection known as collective immunity. Vaccines may need to be changed to keep up with the virus as it progresses, and people may need regular boosters to maintain their protection.

“We need more research to understand how long immunity can last for people exposed to SARS-CoV-2 and why some of these second infections, although rare, present as more serious,” explains the study author Mark Pandori, PhD, of the State of Nevada. Public health laboratory, said in a press release.

“So far we’ve only seen a handful of cases of re-infection, but that doesn’t mean there aren’t more, especially since many cases of COVID-19 are asymptomatic, ”he said. “At the moment, we can only speculate on the cause of the reinfection.”

Researchers stress that everyone should protect themselves from COVID-19 infection, even if they are sure they have had it before, by wearing a face mask in public, staying at least six feet from others and washing and disinfecting your hands often.


Akiko Iwasaki, PhD, Waldemar Von Zedtwitz Professor of Immunobiology and Molecular, Cellular and Developmental Biology; Researcher, Howard Hughes Medical Institute, Yale School of Medicine, New Haven, CT.

The Lancet, October 1, 2020.

Clinical infectious diseases, September 19, 2020.

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