CLEVELAND, Ohio — Researchers in the United States have confirmed a case of COVID-19 reinfection, suggesting that people who recover from the illness might not develop immunity. The case is believed to be the first North American case of reinfection with COVID-19.
A 25-year-old Nevada man tested positive for COVID-19 in April and again in June, separated by two negative tests, according to a case study published Monday in the Lancet. The man was infected with two different strains of the coronavirus, the study said.
The patient’s second bout of COVID-19 was worse than the first, requiring hospitalization and assistance in breathing, the study said.
“The implications of these data are that SARS-CoV-2 can adapt with enough genetic dexterity to avoid a natural immune response in a manner to re-establish detectable levels of infection in an individual,” the study said.
This data has implications for future COVID-19 vaccines. It may mean that initial exposure to the coronavirus “does not result in a level of immunity that is 100% protective for all individuals,” researchers wrote.
The Lancet study stressed that COVID-19 reinfection is rare. Nevertheless, everyone, whether they previously had the illness or not, should continue taking precautions to avoid infection.
Researchers on the Lancet case study, most of whom are based in Reno, Nevada, aren’t certain why the man became sicker during his second illness. The patient many have picked up a high dose of the coronavirus, or a more virulent version of the virus, the study said.
Another possibility is that the presence of antibodies in his bloodstream made the second infection worse; this phenomenon has been observed in other diseases such as dengue fever.
The Nevada case is the fifth confirmation of COVID-19 reinfection globally.
The first documented case of reinfection was identified in Hong Kong in August.
Other reinfection cases have been found in Belgium, the Netherlands and Ecuador. The cases from Belgium and the Netherlands did not show any difference in the severity of symptoms, according to press reports.
Researchers on the Lancet study noted that the Nevada case and other confirmed reinfection cases involved patients with COVID-19 symptoms. It’s possible, the study noted, that many infections and reinfections happen among asymptomatic people, and are undetected.