People who've had COVID-19 two or more times have more than twice the risk of dying and three times the risk of being hospitalized within six months of their last infection, compared to people who've only been infected once, according to a preliminary study from researchers at Washington University in St. Louis.
"We asked a simple question that if you got COVID-19 before and now you're on your second infection, does this really add risk? And the simple answer is that it does," Ziyad Al-Aly, MD, study author and clinical epidemiologist at Washington University, told CNN.
Researchers used electronic healthcare databases from the VA health system to build a cohort of more than 5.6 million patients. This included 257,427 people with one documented infection; 38,926 people with two or more infections; and a non-infected control group of more than 5.3 million. Those with reinfections had a higher risk of death, hospitalization and other health problems compared to those with one infection, according to the preliminary findings posted June 17 on the preprint website Research Square.
Chest pain, abnormal heart rhythms, inflammation of the heart muscle and blood clots were among new diagnoses that were common after reinfections. Common lung issues included shortness of breath and fluid accumulation around the lungs, Dr. Al-Aly told CNN.
The risk of new health problems was highest right after acute infection, though the risk continued for at least six months. The risks also increased in a graded fashion: "That is, risks were lowest in people with one infection, increased in people with two infections, and highest in people with three or more infections," researchers said.
Reinfections have become more common with the rise of variants adept at evading immune protection from vaccination or prior infection. CDC estimates show omicron subvariant BA.5 — which has been shown to be better at escaping neutralizing antibody responses than earlier variants — is now dominant in the U.S, accounting for nearly 54 percent of cases.
"The evidence suggests that for people who already had a first infection, prevention of a second infection may protect from additional health risks," the study said. "Prevention of infection and reinfection with SARS-CoV-2 should continue to be the goal of public health policy."