The case for COVID vaccine heart protection has grown stronger, even as most Americans skip their seasonal shots. A new study drawing on data from more than a million patients finds that updated COVID-19 vaccines continue to guard against cardiovascular disease, with the greatest benefit for older adults and those with underlying health conditions.

What the Study Found

Despite widespread hesitancy around seasonal COVID-19 vaccines, the updated shots still deliver meaningful protection, particularly for people over age 75 and those with existing medical issues. The findings come from a large analysis pulling data from a U.S. Department of Veterans Affairs health system.

The research builds on earlier evidence that the vaccines significantly reduce COVID-related cardiovascular risks, especially heart attacks and strokes. What made this study notable is that the continued benefit wasn’t a foregone conclusion. As the virus evolved, the vaccines were updated, population immunity rose from prior infection and vaccination, and the risk of severe outcomes declined, all factors that could have weakened the protective effect over time.

A Closer Look at the Numbers

Published in JAMA Internal Medicine, the study focused on whether the 2024-2025 COVID-19 vaccine still protected against what researchers call major adverse cardiovascular events, or MACE. These include cardiovascular death, heart attack, stroke, and hospitalization for heart failure.

The scale of the analysis was substantial:

• It included electronic medical record data from 1,039,659 patients in the VA’s St. Louis Health Care System.
• All patients received a seasonal flu shot between September and December 2024, with some also getting a COVID-19 vaccine at the same time.
• Of those, 349,085 received both shots, while 690,574 got only the flu shot and served as the control group.

After eight months of follow-up, the researchers compared MACE events between the two groups. The COVID shot’s overall vaccine effectiveness against MACE was 38 percent.

In absolute terms, the benefit was modest. The study estimated that the shots lowered the rate of COVID-associated MACE events from roughly 5 in 10,000 to 3 in 10,000. Across subgroups, the protection was strongest among those aged 75 and older and people with underlying health conditions.

Hints of an Even Broader Benefit

The research team, led by epidemiologist Ziyad Al-Aly at the St. Louis VA, also examined MACE and deaths in cases where no COVID-19 infection was documented. Here, the vaccine’s benefits appeared even stronger, a pattern suggesting that some COVID-19 cases may have gone missed or undiagnosed.

In this broader analysis, the shots appeared to reduce the rate of MACE from 382 per 10,000 to 358, and the rate of death from 223 to 207. Extrapolating to a population of one million people, the researchers estimated that vaccination could plausibly avert around 2,370 MACE events and 1,580 deaths over eight months, though they urged caution in interpreting that figure.

Important Limitations

Like any study, this one has constraints worth noting. Chief among them is that the U.S. veteran population studied is largely older, White, and male, which makes it likely the findings can’t be neatly generalized to the entire population.

Even so, the results reinforce that the vaccines continue to offer cardiovascular protection, a factor people may want to weigh when deciding whether to get an annual booster. A companion study published the same day found the vaccines still directly protect against COVID-19 as well, reducing the risk of hospitalization by 35 percent and critical illness by 41 percent.

Strong Evidence Meets Falling Uptake

The scientific picture stands in sharp contrast to public behavior. In an accompanying editorial, cardiologist and former FDA commissioner Robert Califf wrote that the two studies provide strong evidence of a favorable benefit-to-risk balance for updated COVID-19 boosters across the population.

Yet he expressed frustration that this evidence is being overshadowed by what he described as general anti-vaccination messaging from the U.S. Department of Health and Human Services, now led by Health Secretary Robert F. Kennedy Jr.

The vaccination numbers underscore his concern. According to federal data, only 17.5 percent of U.S. adults and 22.6 percent of people over 65 have received the 2025-2026 COVID shot.

Califf argued that the politicization of COVID-19 vaccination, and mRNA vaccines more broadly, has taken a real toll on the longevity and functional health of Americans. He called for researchers to gather more data on the vaccines’ benefits and to engage directly with the public, including on social media, to counter anti-vaccine rhetoric.

The Bottom Line

Taken together, these findings add to a growing body of evidence that COVID-19 vaccines offer protection extending beyond the respiratory system to the heart, particularly for those at highest risk. While the absolute benefit may be modest for the general population, it appears most significant for older adults and people with chronic conditions.

As always, the decision about whether to get a booster is a personal one best made in consultation with a healthcare provider who understands your individual risk factors. Given that this topic touches on broader public health debates, anyone weighing the choice may find it helpful to focus on the evidence and discuss their specific situation with a trusted medical professional.