A new study published in JAMA Internal Medicine has found that the updated COVID-19 vaccines continue to offer significant protection against cardiovascular disease. The study analyzed data from over 1 million patients in a US Department of Veterans Affairs health system and found that the vaccines reduced the risk of major adverse cardiovascular events (MACE) by 38 percent.
The researchers included electronic medical record data from 1,039,659 patients in the VA’s St. Louis Health Care System. All of the 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 the 1,039,659 patients, 349,085 received both shots, while 690,574 got just the flu shot.
After eight months of follow-up, the researchers looked for documented COVID-19 cases and compared MACE events among the two groups. The study found that the benefits were strongest among those aged 75 and older and those with underlying health conditions. In terms of absolute numbers, the benefit is modest, but significant, dropping the rate of COVID-19-associated MACE events from about 5 in 10,000 to 3 in 10,000.
The study also found that the benefits of COVID-19 vaccines were stronger when looking at MACE and deaths without documented COVID-19 cases. This suggests that COVID-19 cases may have been missed or undiagnosed. The shots appeared to drop the rate of MACE from 382 per 10,000 to 358, and the rate of death from 223 to 207.
The researchers estimate that vaccination could plausibly be associated with averting approximately 2,370 MACE events and 1,580 deaths over an 8-month period. However, they urge caution in interpreting the finding due to limitations of the study, including that most of the US veteran population is older, White, and male.
The findings indicate that the vaccines continue to offer cardiovascular protection against COVID-19, which should factor into people’s decisions on whether to get an annual COVID-19 booster. An accompanying study also published in JAMA Internal Medicine found that the vaccines still directly protect against COVID-19, reducing the risk of hospitalization and critical illness by 35 percent and 41 percent, respectively.
In an accompanying editorial, cardiologist and former Food and Drug Administration commissioner Robert Califf wrote that the data from the two studies ‘provide strong evidence of a favorable balance of benefit to risk for updated COVID-19 vaccine boosters across the population.’ However, he lamented that despite this strong evidence, national views are being swayed by anti-vaccine rhetoric.
Only 17.5 percent of adults and 22.6 percent of people over age 65 in the US have gotten the 2025–2026 COVID shot, according to federal data. Califf called for researchers to collect more data on the vaccine’s benefits and engage with the public about the findings, particularly on social media.
Source: Original article