New Study Explains Why Repeat COVID Infections Are Dangerous

The more times you’re infected with COVID-19, the higher your risk for severe symptoms, hospitalization, and death, according to a new study published in Nature Medicine.

The researchers used data collected from patients in the Department of Veterans Affairs (VA) database, including more than 443,000 who had been infected once, almost 41,000 who had had two or more infections, and more than five million who had never had a COVID infection.

They found that people infected with COVID two or more times had more than double the risk of death and triple the risk of hospitalization compared to someone who was infected once, regardless of vaccination status.

People who were reinfected were also more likely to develop long COVID and chronic conditions, such as diabetes, heart disease, and blood clotting disorders. These risks were the highest in patients who had three or more infections.

The new findings challenge existing ideas that having a prior COVID infection offers strong protection against new infections.

“We were told before that if you get it once, you build immunity, and maybe reinfection is inconsequential,” said Ziyad Al-Aly, MD, FASN, a co-author of the study and chief of the Research and Education Service at the VA St. Louis healthcare system. “Well, we’re saying here that the infection is not inconsequential.”

“A sore throat and fever for a day or two—a lot of us can tolerate that. The larger concern is the long-term ramifications of the infection,” Al-Aly said.

Prior Infection Doesn’t Lower the Risk of the Negative Health Effects

The study did not measure whether having immunity reduces the risk of reinfections. However, based on previous reports, natural immunity from prior infections is not as robust as vaccine-induced immunity.

“There are consequences of getting your immunity through infection, which this paper is starting to flesh out. Vaccination is safer than infection in any context,” Andrew Pekosz, PhD, a virologist and professor at Johns Hopkins Bloomberg School of Public Health, told Verywell.

The new study also sheds light on the importance of avoiding infection at all costs, not only for the sake of avoiding severe illness and death, Pekosz added.

“It really is sobering,” he said. “It starts to tell us what the true cost of COVID-19 is.”

Is There Anything We Can Do to Reduce the Risk of Reinfections?

Moving forward, Al-Aly and his team will seek to investigate how to reduce the risks of reinfections and the health consequences.

“The main message is if you’ve had COVID-19 before, it’s worth it to go ahead to protect yourself from getting it again,” Al-Aly said. “The infection is not benign.”

The study findings may prompt doctors and researchers to revise future COVID-19 strategies. Fighting the virus should involve additional efforts in reducing the risk of getting infected, Pekosz said. This could mean that vaccine manufacturers will have to optimize booster development and rollouts, and potentially develop a vaccine that can target transmission, he added.

In the meantime, Pekosz said people need to utilize available treatments to the best of their ability and take public health precautions. This means masking indoors, avoiding crowded spaces, and seeking treatments like Paxlovid to shorten the duration of your infection.