US Reports First Confirmed COVID-19 Reinfection Patient

A 25-year-old male in Nevada has become the first US citizen confirmed to have suffered a reinfection of coronavirus 2019 (COVID-19).

A new case study published in The Lancet Infectious Disease Monday evening describes a young adult male in Washoe County who tested positive for 2 distinct SARS-CoV-2 variants within a 48-day timeframe, while having had 2 separate negative test results in between positive cases.

Worldwide, the patient becomes the fifth known to clinicians and investigators to have been confirmed with a reinfection—following cases in Belgium, the Netherlands, Hong Kong, and Ecuador each—and only the second, following Ecuador, to result in a worse disease outcome on the second infection.

The second infection, Nevada State Public Health Laboratory investigators noted, resulted in his hospitalization and need for oxygen support. As such, the findings challenge proposals that initial COVID-19 exposure could be associated with total immunity.

More concretely, the unique case supports the idea that the unknowns surrounding SARS-CoV-2 infection and immune response are still great, lead author Mark Pandori, PhD, of the University of Nevada, Reno School of Medicine, said in a statement.

“It is important to note this is a singular finding and does not provide generalizability of this phenomenon,” Pandori said. “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.”

Pandori and colleagues observed that the unnamed re-infected patient had initially tested positive for SARS-CoV-2 in April 2020. He then tested negative for the virus post-recovery on 2 separate instances. In June, the patient began to experience severe symptoms of COVID-19: fever, headache, dizziness, cough, nausea, and diarrhea.

Once hospitalized, the patient tested positive for the virus again. He has since been discharged from the hospital and has made another full recovery.

Pandori and colleagues observed significant genetic differences in the genome sequences from the patient’s virus samples from April and June. Currently, they are only capable of speculating about what causes reinfection.

“We need more research to understand how long immunity may last for people exposed to SARS-CoV-2 and why some of these second infections, while rare, are presenting as more severe,” Pandori said. “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.”

Regarding the worsened disease outcome on the second infection, investigators suggested a series of possible explanations. First, the patient may have been exposed to a much greater dose of the virus, leading to a more acute reaction in June. Next, the patient may have come in contact with a more virulent version of COVID-19. Another theory is antibody dependent enhancement, which has been known to worsen infection burden in patients with previous SARS-CoV viruses or dengue fever.

Another 2 theories—which investigators stressed have lesser possibility—include the notion of virus mutation, as well as multiple strain co-infection in April.

In an interview with Contagion, Pandori said a more substantial dosage of the virus may have led to the more severe subsequent infection.

"But one of the other things to consider is that as a viral pandemic continues over time, the virus is changing over time, he said. "And there may be consequences to that."

What's already believed is that changes to the virus' genetics have led to structural changes that may have changed the nature by which the virus functions or infects people, he explained.

"And that might even have been the cause of this—we don’t know," Pandori said.

As investigations of the virus continue, Pandori stressed the need for continued precautions—including social distancing, handwashing, and wearing face masks—among all individuals, including those who have previously tested positive.