Many people worldwide are experiencing repeat SARS-CoV-2 infections, but the health risks associated with these reinfections have remained unclear. Now,  a team of researchers led by Washington University in St. Louis has found that repeated COVID-19 infections increase the risk of organ failure and death.

“During the past few months, there’s been an air of invincibility among people who have had COVID-19 or their vaccinations and boosters, and especially among people who have had an infection and also received vaccines; some people started to referring to these individuals as having a sort of superimmunity to the virus,” said study senior author Dr. Ziyad Al-Aly. 

“Without ambiguity, our research showed that getting an infection a second, third or fourth time contributes to additional health risks in the acute phase, meaning the first 30 days after infection, and in the months beyond, meaning the long COVID phase.”

The results of the study also indicate that the risk seems to increase with each infection. “This means that even if you’ve had two COVID-19 infections, it’s better to avoid a third. And if you’ve had three infections, it’s best to avoid the fourth.”

Dr. Al-Aly emphasized that limiting exposure to the virus is especially important as the U.S. heads into the winter months, with new variants emerging, mutating and already causing an upswing in infections in some parts of the country.

“People should do their best to prevent repeat infections by masking, for example, getting all of their eligible boosters, staying home when sick. Also, get a flu shot to prevent illness. We really need to do our best to reduce the chance we will have a twin-demic of both COVID-19 and the flu this winter season.”

For the investigation, the researchers analyzed 5.8 million medical records in a database maintained by the U.S. Department of Veterans Affairs. The team used statistical modeling to assess the health risks of COVID-19 reinfections within the first 30 days after contracting the virus, and then up to six months later.

The analysis revealed that people with COVID-19 reinfections were twice as likely to die and three times more likely to require hospitalization. 

Furthermore, patients with repeat infections were 3.5 times more likely to develop lung problems, three times more likely to suffer heart conditions and 1.6 times more likely to experience brain conditions.

“Our findings have broad public health implications as they tell us that strategies to prevent or reduce the risk of reinfection should be implemented,” said Dr. Al-Aly. “Going into the winter season, people should be aware of the risks and practice vigilance to reduce their risk of infection or reinfection with SARS-CoV-2.” The study is published in the journal Nature Medicine.