The latest iteration of the COVID-19 vaccine, the 2024-2025 formulation, has been associated with a reduced incidence of serious heart-related events among U.S. veterans, according to a new study. The research confirmed a modest decrease in COVID-19-associated major adverse cardiovascular events (MACE) in those who received the vaccine.
MACE is a comprehensive measure encompassing severe cardiac outcomes such as cardiovascular death, heart attack, stroke, and hospitalizations for heart failure. The study utilized health records from the U.S. Department of Veterans Affairs, comparing nearly 350,000 veterans who received both the COVID-19 and flu vaccines simultaneously with almost 700,000 veterans who received only the flu vaccine.
The cohort studied had an average age of approximately 70, with 92% being male. Over an eight-month period, the findings revealed that individuals who received the 2024-2025 COVID-19 vaccine exhibited a lower risk of COVID-associated MACE, demonstrating a relative vaccine effectiveness of 37.7%.
Specifically, the COVID-19 vaccine was linked to a 57.9% lower risk of cardiovascular death, a 38.5% reduction in heart attack risk, and a 41.9% decrease in the risk of hospitalization for heart failure. The study did not find a statistically significant association with a reduced risk of stroke.
Key Findings and Demographics
The protective effect of the vaccine was most pronounced among older adults and those with pre-existing health conditions. In veterans aged 75 and older, the vaccine demonstrated 50.7% effectiveness in preventing COVID-associated MACE.
While the study highlights an association, its observational nature means it cannot definitively establish a cause-and-effect relationship between the COVID-19 vaccine and the observed reduction in cardiovascular events.
Dr. Glenn Hirsch, a cardiologist not involved in the research, commented that the results align with previous studies suggesting vaccines can prevent cardiovascular events. He explained that acute inflammation caused by infections like COVID-19 can heighten the risk of cardiovascular issues, potentially leading to increased clotting or the rupture of arterial plaques. Vaccines, by preventing infection or mitigating its severity, can subsequently lower this inflammation and, consequently, the cardiovascular risk.
Hirsch noted that the overall benefit observed in this study was less pronounced than in prior research. This could be attributed to the reduced severity of recent COVID-19 variants, existing immunity from prior infections, and a decline in COVID-19 testing, which makes linking cardiovascular events directly to the virus more challenging.
Despite these factors, Hirsch emphasized that evidence continues to support the benefit of COVID-19 vaccination, recommending that individuals discuss annual vaccinations with their healthcare providers. He also acknowledged that observational studies may have limitations, including potential confounding factors and the possibility of uninvestigated adverse effects.
