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A recent study published in *JAMA Internal Medicine* has revealed that the updated COVID-19 vaccine significantly reduces the risk of serious cardiovascular events among elderly individuals. The research, conducted by scientists from the U.S. Department of Veterans Affairs and Washington University in St. Louis, analyzed electronic health records of over one million American veterans who received the flu vaccine between September and December 2024. Of these, 349,085 also received the updated COVID-19 vaccine on the same day. This approach was designed to minimize the so-called “healthy vaccinee bias,” which assumes that individuals who get vaccinated generally have better overall health behaviors.

The participants were monitored for up to eight months, during which researchers recorded four major cardiovascular outcomes linked to COVID-19: death due to cardiovascular events, acute myocardial infarction (heart attack), stroke, and hospitalization for heart failure. According to the findings, the benefits of the vaccine were most pronounced in individuals aged over 75 years, where there was a 50.7% reduction in cardiovascular events. However, the results were not statistically significant for other age groups, meaning the protective effect against cardiovascular episodes could not be confirmed with certainty for these demographics. The average age of the participants was 70 years.

The study highlights that for every 10,000 people vaccinated, two severe cardiovascular events related to COVID-19 were avoided compared to those who did not receive the vaccine. When considering all cardiovascular events—not just those definitively linked to COVID-19—the number rises to approximately 24 events prevented per 10,000 individuals. In a population of one million people, the authors estimate that vaccination could prevent around 1,580 deaths and 2,370 adverse cardiovascular events within eight months.

The effectiveness of the vaccine was found to be statistically significant across both subgroups with and without pre-existing conditions. Nevertheless, the absolute benefit was notably greater among individuals with existing health issues such as cardiovascular disease, chronic kidney disease, chronic lung disease, diabetes, and immunosuppression. Researchers caution, however, that this projection should be interpreted carefully, given the observational nature of the study and its focus solely on American veterans—a predominantly white, male, and older population.

The study also notes that the current efficacy of the vaccine is lower than that observed in the early years of the pandemic. This decline is attributed to the evolution of the virus, immunity gained from previous infections, and the increased difficulty in detecting infections in a scenario where testing frequency has decreased.

The research suggests that infection with SARS-CoV-2 triggers inflammatory and clotting processes that damage blood vessels and increase the risk of thrombosis, which can lead to heart attacks or strokes. By reducing the severity of the infection, the vaccine mitigates these vascular-damage mechanisms. Additionally, the researchers emphasize that the benefits observed for cardiovascular events of non-COVID-related causes were much more substantial than those seen in cases definitively associated with the virus.

The study underscores the importance of continued vaccination efforts, particularly among high-risk populations, despite the limitations of the research design. It calls for further studies involving more diverse populations to validate these findings and better understand the broader implications of the vaccine's impact on cardiovascular health. As the understanding of long-term effects of the virus continues to evolve, this research adds another layer to the ongoing discussion about the comprehensive benefits of vaccination beyond preventing direct infection.