COVID Vaccine Confirms Reduced Heart Disease Risk in Over 1 Million Patients

According to a report by Ars Technica, a study based on data from more than one million patients in the U.S. Department of Veterans Affairs (VA) healthcare system has confirmed that the 2024–2025 season COVID-19 vaccine continues to reduce the risk of cardiovascular disease. The study was published in JAMA Internal Medicine.

It is already widely recognized that COVID-19 infection can have serious cardiovascular effects. The inflammatory response triggered by the viral infection has been reported to cause blood clot formation and damage to the vascular endothelium, increasing the risk of heart attack, stroke, and heart failure. Earlier studies showed that initial vaccination significantly reduced these risks, but as the virus mutates, vaccines are updated regularly, and immunity (both from infection and vaccination) builds at the population level, it was necessary to verify how well this protective effect is maintained.

Study Design and Results

The research team analyzed electronic health record data from the St. Louis VA Healthcare System. The study included 1,039,659 patients who received a seasonal influenza vaccine between September 3 and December 31, 2024. Of these, 349,085 also received a COVID vaccine at the same time, while the remaining 690,574 received only the influenza vaccine and served as the control group.

After eight months of follow-up, the researchers compared the rates of confirmed COVID-19 infection and major adverse cardiovascular events (MACE: cardiovascular death, heart attack, stroke, or hospitalization for heart failure) between the two groups. They found that the COVID vaccine had a 38% preventive effect against MACE.

In absolute risk terms, the effect is modest: the estimated incidence of COVID-related MACE dropped from about 5 to 3 per 10,000 people. While this number may seem small, it carries greater significance for high‑risk populations.

Notable Efficacy in the Elderly and Those

with Underlying Conditions

Subgroup analysis showed that the vaccine’s effect was particularly pronounced in patients aged 75 and older and in those with underlying conditions. These groups already have a higher baseline risk of severe COVID-19 and cardiovascular complications, so a 38% relative risk reduction translates into a larger number of absolute events prevented.

The research team also performed an analysis that included cases without documented COVID-19 infection. In this analysis, the MACE rate in the vaccinated group fell from 382 to 358 per 10,000 people, and mortality dropped from 223 to 207. The researchers note that this may suggest the presence of undiagnosed COVID-19 infections. When extrapolated to a population of one million, they estimate that about 2,370 MACE events and 1,580 deaths could be averted. However, they caution against overinterpreting these findings.

Study Limitations

Caution is needed when generalizing these results. VA healthcare users are predominantly older white men, so the findings may not apply directly to younger individuals, women, or other racial/ethnic groups. In addition, the data come from an observational study, and adjustments for confounders may not be complete. Self‑selection bias—where vaccine uptake is more common among health‑conscious individuals—should also be considered.

Impact of Anti-Vaccine Rhetoric

These results clearly demonstrate the continued benefits of vaccination. Yet in the United States, many people do not receive the seasonal COVID vaccine. A major factor is the spread of anti‑vaccine rhetoric through social media and other channels. For example, misinformation claiming that COVID vaccines cause myocarditis has circulated widely, even though this study actually demonstrates a preventive effect against cardiovascular events.

Such distortions in information flow are not unrelated to platform design and advances in AI technology. For instance, next‑generation operating systems like Huawei HarmonyOS 7 with integrated AI agent Xiaoyi use AI agents to shape users’ information environments. Ensuring the reliability of health information will become an increasingly important responsibility for technology platforms.

From the perspective of maintaining preventive interventions over time, there is a structural similarity to addressing aging infrastructure, such as the situation described in Russia appears set to finally address long-term, serious space station cracks. Vaccination is a form of preventive maintenance that requires continuous updates and adaptation in response to viral mutations and waning immunity.

Editorial Opinion

In the short term, this evidence will likely be used to promote vaccination for the 2026–2027 season. It provides strong grounds for doctors to recommend the vaccine, especially to older adults and those with high cardiovascular risk. However, in communities where anti‑vaccine sentiment is entrenched, presenting numbers alone is unlikely to change behavior. Public health authorities need to explore new communication strategies to counter misinformation. For instance, personalized recommendations from primary care physicians or messaging through trusted community leaders may be more effective.

Over the long term, the question is how well mRNA vaccine technology can sustain its cardiovascular protective effects. This study is based on a single season’s data, so it is essential to verify the durability of the effect over multiple years and the effectiveness of updated vaccines against new variants. Research in diverse populations beyond the VA cohort—particularly younger people, women, and non‑white groups—is also needed. Furthermore, future studies should examine possible synergistic effects of simultaneous influenza and COVID vaccination and elucidate the underlying mechanisms of cardiovascular protection.

As an editorial board, we raise the following question: How should technology respond to changes in the information environment that are driving down vaccination rates? Personalized health information delivered by AI agents carries the risk of deepening filter‑bubble divides. Ensuring access to reliable health information is not merely a medical issue; it is a social responsibility that the entire technology industry must address.

References

• Ars Technica “Heart protection from COVID shots remains amid updates, study finds” — Published June 15, 2026 (https://arstechnica.com/health/2026/06/covid-vaccines-still-protect-against-heart-problems-large-study-finds/)
• JAMA Internal Medicine (original article referenced)