A recent study published in The Lancet has revealed significant findings about Long Covid, also known as post-acute sequelae of Covid-19 (PASC). Conducted by researchers from the Renaissance School of Medicine at Stony Brook University and the Stony Brook World Trade Center Health and Wellness Program, the study identified 475 patients with Long Covid. Notably, nearly 85 percent of these patients had experienced multiple Covid-19 infections over a four-year period from March 2020 to February 2024.
The research highlights that vaccination independently reduced the risk of developing Long Covid in individuals who were vaccinated before contracting the virus. This study is one of few with such a large sample size that examines risk factors for Long Covid.
Lead author Sean Clouston, PhD, Professor at RSOM, stated: “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.” Clouston further explained that after adjusting for demographic and clinical variables, there was a statistically significant link between multiple infections and the risk of experiencing PASC.
The patients in this study were part of a group of over 2,500 first responders previously infected with Covid-19. These individuals are monitored by the Stony Brook WTC Health and Wellness Program for complications arising from their infections. Dr. Benjamin Luft, Director of the Program, led efforts to identify those with Long Covid symptoms such as fatigue and neurological conditions.
Due to a lack of diagnostic tests for Long Covid, researchers followed World Health Organization guidelines to identify cases. Participants with persistent or new symptoms emerging within three months after initial infection were categorized as having Long Covid.
Dr. Luft emphasized: “There are some possible pathogenic mechanisms that cause Long Covid, but the entire spectrum of its risk factors remains unknown.” He highlighted the importance of identifying specific risk factors like re-infection or lack of vaccination to better understand and manage this condition.
The study authors stress prevention as key to avoiding Long Covid but underscore vaccination's role in reducing risk. They noted: “Among those who later developed PASC, we found that the risk...was much higher among individuals who were unvaccinated at the time.”
This research received support from several grants provided by institutions including the National Institutes of Health’s National Institute on Aging and National Institute for Occupational Safety and Health.