Study: Multiple SARS-CoV-2 infections increase risk for long COVID
Key takeaways:
- Nearly 85% of people with long COVID had experienced multiple SARS-CoV-2 infections.
- Other factors that increased the risk were hypertension, more severe infection and being unvaccinated.
The vast majority of people in a study with long COVID had experienced multiple SARS-CoV-2 infections over the course of a 4-year period, researchers reported.
“While it is possible that the causes of long COVID could be many and variable depending on the patient population studied, with this cohort the evidence is clear that by having COVID numerous times, patients became more at-risk for developing long COVID,” Sean Clouston, PhD, professor in Stony Brook University’s Renaissance School of Medicine, said in a press release.
Although there is evidence that the prevalence of long COVID among people with previously documented COVID-19 has declined — partially because of the effects of vaccination — experts have said the risk remains substantial. For some patients, symptoms can persist for years.
To determine whether multiple SARS-CoV-2 infections impact the risk for long COVID, Clouston and colleagues retrospectively studied data from 2,511 essential workers in New York, most of whom were first responders, who had COVID-19 between March 2020 and Feb. 29, 2024.
According to the study, 475 participants developed long COVID (18.9%; 95% CI = 17.1%-20.5%), 403 of whom had multiple SARS-CoV-2 infections — meaning that nearly 85% of people in the study with multiple infections also developed long COVID.
Overall, the researchers found significant associations between the risk for developing long COVID and having multiple SARS-CoV-2 infections (RR = 1.41; 95% CI, 1.14-1.74), a severe case of COVID-19 (RR = 3.17; 95% CI, 2.41-4.16) and being unvaccinated against COVID-19 before an initial SARS-CoV-2 infection. People who developed long COVID also were more likely to have a history of hypertension (37.9% vs 31.8%), the researchers noted.
“There are some possible pathogenic mechanisms that cause long COVID, but the entire spectrum of its risk factors remains unknown,” Benjamin Luft, MD, director of Stony Brook’s WTC Health and Wellness Program and professor in the university’s Renaissance School of Medicine, said in the release. “This is why our study and future ones are so important. Identifying specific risk factors such as reinfection or lack of vaccination can assist in better understanding and managing the condition.”
References:
- Babalola TK, et al. Lancet Reg Health Am. 2025;doi:10.1016/j.lana.2024.100984.
- Study: Multiple COVID infections associated with long COVID. https://sbmatters.stonybrook.edu/study-multiple-covid-infections-associated-with-long-covid/. Published Jan. 22, 2025. Accessed Jan. 24, 2025.
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