COVID Boosters Still Cut Major Heart Risks, VA Study Finds

Updated COVID Vaccines Show Continued Cardiovascular Benefit

Updated COVID-19 shots continue to reduce the risk of serious cardiovascular complications linked to infection, according to a large new study using data from the US Department of Veterans Affairs health system. The findings are notable because they suggest the benefit has held up despite viral evolution, updated vaccine formulations, and broad changes in population immunity.

The study, published in JAMA Internal Medicine and summarized in the source material, focused on major adverse cardiovascular events, or MACE. That category includes cardiovascular death, heart attack, stroke, and hospitalization for heart failure. Researchers found that the 2024-2025 COVID-19 vaccine remained protective against these outcomes.

More Than 1 Million Patients Included

The analysis used electronic medical record data from 1,039,659 patients in the VA St. Louis Health Care System. All patients received a seasonal influenza shot between September 3, 2024, and December 31, 2024. Among them, 349,085 also received a COVID-19 vaccine at the same time, while 690,574 received only the flu shot and served as the control group.

Researchers then followed patients for eight months, tracking documented COVID-19 cases and comparing cardiovascular outcomes between the groups. Overall vaccine effectiveness against MACE events was reported at 38%.

In absolute terms, the reduction was modest but meaningful. The study estimated that COVID vaccination lowered the rate of COVID-associated MACE events from about 5 in 10,000 to 3 in 10,000. For population-level medicine, those shifts matter because cardiovascular events are among the most severe downstream consequences of infection.

Who Benefited Most

The source says the strongest benefits appeared among people aged 75 and older and among those with underlying medical conditions. That pattern aligns with broader clinical expectations. Older adults and medically vulnerable patients carry higher baseline risks both from COVID infection and from cardiovascular complications triggered or worsened by infection.

The study builds on earlier evidence that COVID vaccination can reduce not just acute illness but also some of the systemic damage associated with infection. In this case, the emphasis is on heart attacks, strokes, heart-failure hospitalizations, and cardiovascular deaths that follow COVID cases.

Why the Result Matters Now

One reason the finding stands out is that it was not guaranteed to persist. COVID has changed repeatedly, vaccine compositions have been updated, and many people now have some combination of vaccine-derived and infection-derived immunity. At the same time, public perception of risk has fallen sharply, and seasonal COVID vaccination uptake has weakened.

The source notes that anti-vaccine rhetoric has contributed to that decline. Against that backdrop, evidence of continued protection against serious non-respiratory complications becomes especially relevant. Public discussion often centers on whether vaccines prevent infection or reduce respiratory severity, but cardiovascular protection is a separate and important outcome.

• The study included more than 1 million VA patients.
• The 2024-2025 COVID vaccine was associated with 38% effectiveness against major cardiovascular events linked to COVID.
• Benefits were strongest in adults 75 and older and in those with underlying conditions.

The numbers do not imply that vaccination eliminates cardiovascular risk, nor do they mean every patient receives the same degree of benefit. But they reinforce a consistent message from post-pandemic research: COVID infection can affect the cardiovascular system, and vaccination can lower some of that danger.

That is a practical public-health finding, particularly for older adults and high-risk populations. As COVID vaccination becomes more seasonal and more selective, evidence that updated shots still reduce severe heart-related complications may shape how clinicians and patients weigh the value of another dose.

This article is based on reporting by Ars Technica. Read the original article.