A new study has provided key insights into the risks associated with long COVID, also known as post-acute sequelae of COVID-19 (PASC).
Researchers found that nearly 85% of the 475 patients identified with long COVID had experienced multiple COVID-19 infections between March 2020 and February 2024.
Importantly, being vaccinated before contracting COVID-19 significantly reduced the risk of developing this chronic condition.
The study, conducted by researchers at the Renaissance School of Medicine (RSOM) at Stony Brook University, in collaboration with the Stony Brook World Trade Center (WTC) Health and Wellness Program, offers one of the most comprehensive assessments of long COVID in the post-pandemic era.
Published in The Lancet Regional Health—Americas, the findings shed light on how repeated infections and vaccination status impact the likelihood of developing long COVID.
Repeated Infections Increase Risk
The study tracked 2,500 first responders who had previously contracted COVID-19 and were being monitored for related complications. Among these, 475 patients were diagnosed with long COVID based on the World Health Organization’s criteria.
This definition includes the development of at least one new symptom within three months of the initial infection that persisted for at least two months and could not be explained by other medical conditions.
Patients with long COVID experienced a range of symptoms, including fatigue, brain fog, neurological issues, respiratory problems, and gastrointestinal disturbances.
The researchers noted a clear and statistically significant association: those who had multiple COVID-19 infections were far more likely to develop long COVID than those with a single infection.
“By having COVID numerous times, patients became more at-risk for developing long COVID,” explained lead author Dr. Sean Clouston, a professor at RSOM. This association remained significant even after accounting for demographic, lifestyle, and clinical factors.
The Role of Vaccination
The study also highlighted the protective role of COVID-19 vaccination. Patients who were vaccinated before their first infection had a significantly lower risk of developing long COVID compared to those who were unvaccinated.
This reinforces the importance of vaccination as a preventive measure not just for severe illness but also for reducing the long-term consequences of the virus.
However, the researchers acknowledged that vaccination does not eliminate the risk entirely. Even vaccinated individuals who contract COVID-19 are still at some risk of developing long COVID and should take steps to minimize the severity of infection.
Challenges in Diagnosing Long COVID
Diagnosing long COVID remains complex, as there is no definitive test for the condition. The study followed WHO guidelines to identify patients, ensuring consistency in diagnosis.
For first responders with pre-existing conditions from environmental exposures, such as respiratory illnesses, long COVID symptoms were carefully charted separately to avoid confusion.
Dr. Benjamin Luft, co-author of the study and Director of the WTC Health and Wellness Program, emphasized the need for further research.
“There are some possible pathogenic mechanisms that cause long COVID, but the entire spectrum of its risk factors remains unknown. This is why our study and future ones are so important,” he said.
Implications and Recommendations
The findings highlight the importance of preventing COVID-19 infections, particularly among those at higher risk of long COVID. Vaccination remains a critical tool in reducing this risk. The study also underscores the need for better understanding of the mechanisms behind long COVID to develop effective management strategies.
Researchers hope these insights will guide public health policies and medical interventions to address the growing burden of long COVID. Preventing reinfections, promoting vaccination, and managing symptoms in affected individuals are essential steps in mitigating the long-term effects of the pandemic.
This study adds valuable knowledge to the understanding of long COVID, particularly the heightened risk posed by repeated infections and the protective role of vaccination.
As the world continues to navigate the post-pandemic landscape, such findings emphasize the importance of continued vigilance, vaccination efforts, and further research to better understand and combat this complex condition.
If you care about COVID, please read studies about Vitamin D deficiency linked to severe COVID-19, and how diets could help manage post-COVID syndrome.
For more health information, please see recent studies about new evidence on rare blood clots after COVID-19 vaccination, and results showing zinc could help reduce COVID-19 infection risk.
The research findings can be found in The Lancet Regional Health – Americas.
Copyright © 2025 Knowridge Science Report. All rights reserved.
