Can a person infected with Covid-19 get re-infected with the virus? It seems quite likely, though more research is required into reinfections, say US researchers who studied the case of 25-year-old male patient living in Nevada, US.

In what is being called the first study to confirm a case of Covid-19 reinfection in the US, “researchers found evidence that an individual with no known immune disorders or underlying conditions was infected with SARS-CoV-2 in two separate occurrences,” said a note from The Lancet Infectious Diseases journal, where the study has been published.

The patient was infected with two distinct SARS-CoV-2 variants within a 48-day timeframe, while testing negative in between infections, the study found. “The patient’s second infection was more severe, resulting in hospitalisation with oxygen support, indicating previous exposure to Covid-19 may not translate to guaranteed total immunity, but that further research into reinfections is required,” the note said.

In fact, the authors note that all individuals — whether previously diagnosed or not — should take identical precautions to prevent infection.

Two distinct infections

Giving details on the individual, the note said, after testing positive for SARS-CoV-2 in April 2020, the patient tested negative for the virus on two separate occasions. “In June 2020, after experiencing severe Covid-19 symptoms, including fever, headache, dizziness, cough, nausea, and diarrhea, the patient was hospitalised and tested positive for a second time,” the paper said, adding that he has since been discharged from the hospital and has recovered from the second infection.

“There are still many unknowns about SARS-CoV-2 infections and the immune system’s response, but our findings signal that a previous SARS-CoV-2 infection may not necessarily protect against future infection,” said Mark Pandori of the Nevada State Public Health Laboratory, University of Nevada, Reno School of Medicine, and lead author of the study.

“It is important to note this is a singular finding and does not provide generalisability of this phenomenon. While more research is needed, the possibility of reinfections could have significant implications for our understanding of Covid-19 immunity, especially in the absence of an effective vaccine,” he added.

The genomes of the patient’s virus samples were sequenced in April and June, displaying significant genetic differences between the two cases, implying the patient was infected twice by two distinct SARS-CoV-2 infections, the note said.

At least four other reinfection cases have been confirmed globally in Belgium, the Netherlands, Hong Kong, and Ecuador. However, only the Ecuador reinfection case displayed worse disease outcomes than the first infection, it added.

“So far, we’ve only seen a handful of reinfection cases, but that doesn’t mean there aren’t more, especially as many cases of Covid-19 are asymptomatic. Right now, we can only speculate about the cause of reinfection,” Pandori added.

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