The new 2024-2025 COVID-19 vaccine is linked with fewer serious heart problems in U.S. veterans, showing measurable reductions in major adverse cardiovascular events in a large observational study that compared those who got the COVID shot alongside a flu vaccine to those who received only the flu shot.
Researchers used Department of Veterans Affairs health records to compare two big groups: nearly 350,000 veterans who received the COVID and flu vaccines on the same day and almost 700,000 who received only the flu vaccine. The study population was older, with an average age around 70, and overwhelmingly male at about 92 percent. The analysis tracked outcomes for roughly eight months after vaccination.
The headline finding was a relative vaccine effectiveness of 37.7 percent at preventing COVID-associated MACE, which stands for major adverse cardiovascular events. MACE bundles serious outcomes like cardiovascular death, heart attack and stroke, and often includes hospitalization for heart failure. The protective signal was clearest for cardiovascular death, heart attack and heart-failure hospitalizations, while stroke did not meet statistical significance.
The investigators reported a 57.9 percent lower risk of cardiovascular death, a 38.5 percent lower risk of heart attack and a 41.9 percent lower risk of hospitalization for heart failure among those who received the COVID vaccine. Benefit varied across age groups and clinical profiles, with the strongest effect seen in the oldest patients. People 75 and older had a 50.7 percent reduction in COVID-associated MACE in the study.
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Because the work is observational, it cannot prove the vaccine directly caused the reductions; it only demonstrates a robust association after statistical adjustments. Observational designs always leave room for residual confounding, and the authors acknowledge that limitation. Still, the size and consistency of the signal make the finding noteworthy for clinicians and older adults weighing annual vaccination choices.
Clinical experts noted that this pattern mirrors what has been seen with other vaccines and cardiovascular risk. Dr. Glenn Hirsch called the result “not overall surprising” in comments included with the study coverage. He pointed out how preventing infection or blunting its severity can reduce the acute inflammation that drives many cardiac complications.
“This result is consistent with previous studies of the COVID-19 vaccine and other vaccines against infectious diseases [in] preventing cardiovascular events, including heart attack, cardiovascular cause of death or hospitalizations,” he said. “This can lead to a higher risk of blood clotting, but can also make arterial plaques susceptible to rupture, which then leads to clot formation to heal a ruptured plaque,” he said. “Vaccines either prevent infection or reduce the severity of infection and subsequent inflammation, lowering the cardiovascular risk.”
Hirsch also emphasized that the smaller effect size in this analysis compared with earlier studies could reflect changing realities of the pandemic. Later variants have generally caused less severe acute illness, many people have some immunity from prior infection, and falling rates of testing make it harder to link cardiac events directly to COVID. Those factors can all dilute apparent vaccine benefit in observational data.
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The investigators and commentators urged patients to discuss vaccination with their clinicians and consider individual risks and benefits. They advised annual conversations about infectious disease vaccinations as part of routine care, particularly for older adults and people with chronic conditions. At the same time, they reminded readers that no single study answers every question about safety and longer-term effects.
“The bottom line [is] that there is still evidence of benefit from COVID-19 vaccination like many other infectious disease vaccinations, and people should be encouraged to discuss these with their healthcare team annually,” Hirsch advised. “This is an observational trial and there can always be some confounding after necessary statistical adjustments and other potential benefits or harms, including adverse effects from vaccines that were not investigated in this study,” he added.
