COVID vaccines still protect against heart problems, large study finds
A new study of over one million patients shows that updated COVID-19 vaccines reduce the risk of cardiovascular complications linked to COVID-19, especially in people over 75 and those with underlying conditions.
Despite most Americans skipping seasonal COVID-19 vaccines, the updated shots continue to offer significant protection against cardiovascular disease, according to a new study analyzing data from more than one million patients in the U.S. Department of Veterans Affairs (VA) health system.
The study, published in JAMA Internal Medicine, examined the effectiveness of the 2024–2025 COVID-19 vaccine against “major adverse cardiovascular events” (MACE), including cardiovascular death, heart attack, stroke, and hospitalization for heart failure. Previous research had shown that vaccines lower these risks, but it was unclear whether the benefit would persist as the virus evolved, vaccines were updated, and population immunity increased from prior infection and vaccination.
The researchers used electronic medical records from 1,039,659 patients in the VA’s St. Louis Health Care System. All patients received a seasonal flu shot between September 3, 2024, and December 31, 2024, with some also getting a COVID-19 vaccine at the same time. Of these, 349,085 received both shots, while 690,574 got only the flu shot; the latter group served as the control.
After eight months of follow-up, the team documented COVID-19 cases and compared MACE events between the two groups. Overall, the COVID vaccine’s effectiveness against MACE was 38 percent. In absolute terms, the benefit is modest: the shots reduced the rate of COVID-19-associated MACE from about 5 per 10,000 to 3 per 10,000.
Looking at subgroups, the strongest benefits were seen in those aged 75 and older and those with pre-existing health conditions. The researchers emphasize that updated vaccines remain a crucial tool for preventing severe COVID-19 outcomes, particularly for high-risk populations.
