The coronavirus vaccine reduced the risk of major cardiovascular events linked to covid-19 — strokes, heart attacks, and hospitalization from heart disease — by about 40 percent, according to a new study. The findings, the latest in a growing body of research about the vaccine’s benefits for heart health, suggest such benefits observed in earlier studies have persisted for years.
The study, published Monday in JAMA Internal Medicine, also suggested the vaccine has a broader public health benefit. The vaccine modestly reduced cardiovascular conditions, hospitalizations and deaths of all causes, including those not linked to covid, researchers said.
“It tells us that these vaccines have actually brought beneficial effects even in people who don’t really know that they actually have contracted covid-19,” said Ziyad Al-Aly, a physician-scientist and senior clinical epidemiologist at Washington University in St. Louis and co-author of the study.
Previous studies have indicated the coronavirus vaccine reduces the incidence of heart attacks and strokes, including a study of around 46 million adults in England between 2020 and 2022.
Researchers behind the latest findings set out to determine if those benefits persisted in the years after the onset of the pandemic.
“Vaccine formulations have changed, and also the virus itself has changed over time,” Al-Aly said. But he said they found the more recent vaccine formulas still protected against heart conditions.
The study, conducted among veterans who used the Department of Veterans Affairs health system, examined around 1 million veterans between 2024 and 2025. The research compared those who took the seasonal influenza vaccine and those who opted to take both the flu vaccine and the updated covid-19 vaccine that season. The research reviewed multiple types of vaccines, including mRNA shots and Novavax.
The researchers followed up with the cohorts after around eight months, noting whether they had a covid-19-associated cardiovascular event, defined as a severe heart condition contracted soon after a covid-19 infection.
The cohort that took the covid vaccine had a 37.7% lower risk of covid-associated heart conditions, the study found. The benefit was most pronounced among patients over 75 and those with pre-existing conditions such as cardiovascular disease, diabetes or chronic lung disease.
“To me, this continues to emphasize that we should be encouraging vaccination, especially amongst older individuals,” said Nisha Viswanathan, a physician and director of the Long Covid program at the University of California Los Angeles who was not involved in the study.
Patients who took the covid vaccine were also around 6 percent less likely to suffer from severe heart conditions overall, including ones not linked to a covid-19 infection, according to the study. The vaccine was also associated with reduced deaths and hospitalizations of all causes by around 7 percent.
Al-Aly said that while those percentages appeared low, it still translated to averting around 23 major cardiovascular events, 30 hospitalizations and 16 deaths per 10,000 vaccinated individuals.
“Extrapolating these estimates to a population of 1 million people, vaccination could plausibly be associated with averting approximately 2370 [major cardiovascular] events and 1580 deaths over an 8-month period,” the study states.
Al-Aly and Viswanathan both noted that the study’s population was largely older, White and male, and that the extrapolations on the vaccine’s public health benefit should be treated with caution.
Why did the vaccine produce some protection against heart conditions not connected to a covid diagnosis? Al-Aly suggested that the trend could suggest patients are contracting mild cases of the virus without realizing it.
“This study actually gives us a glimpse of the hidden burden of covid-19 that’s actually still likely circulating in the population,” Al-Aly said.
Viswanathan said that was plausible, but that it was also possible that the covid vaccine could have additional benefits and side-effects on the body. She noted studies have shown that other vaccines can help prevent a wider host of illnesses and chronic conditions, and that research is ongoing on the potential secondary effects of mRNA vaccines such as the covid vaccine.
Covid vaccines have also been linked to a risk of myocarditis and pericarditis, inflammation of the heart muscle and lining, but cases are rare and generally mild, and experts have said the benefits of vaccination outweigh the risk of side effects.
In October, researchers at the University of Florida and the University of Texas published a study that found the covid vaccine improved cancer patients’ responses to immunotherapy.
“MRNA vaccines are doing something else to our system that we haven’t completely understood yet, and I do think there’s probably a lot of positive that is going to come,” Viswanathan said.
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