A major new study has delivered one of the strongest pieces of evidence yet that COVID-19 vaccines are not only safe, but may also offer unexpected long-term heart-health benefits. Published in Nature Communications, the research examined health data from an extraordinary pool of 45.7 million adults, making it one of the largest analyses of its kind since the pandemic began.
The study spans the period between December 2020 and January 2022, covering the rollout of first doses, second doses, and booster shots. By tracking individuals across these phases, researchers were able to look beyond short-term reactions and evaluate how vaccination affected major cardiovascular events—specifically arterial thromboses, which include heart attacks and strokes.
A Significant Drop in Heart Attack and Stroke Risk
One of the most striking findings is that the risk of these life-threatening events fell after vaccination, rather than increased—a direct counter to many myths and misleading claims spread online over the past few years.
According to the study:
After the first vaccine dose, there was a 10% decrease in the risk of arterial thromboses.
After subsequent doses, the protective effects were even stronger.
For Pfizer/BioNTech, the study found around a 20% reduction in major arterial events.
Recipients of the AstraZeneca vaccine saw approximately a 27% reduction after boosters.
These results suggest that the vaccines may help stabilize the body’s inflammatory and immune responses in a way that benefits cardiovascular health—an especially important insight for older adults and individuals living with underlying conditions.
Rare Side Effects Acknowledged — But Extremely Uncommon
The study also approached the topic realistically by addressing rare but known side effects associated with certain vaccines. Cases of myocarditis, for example, were mainly seen in younger males within weeks after receiving mRNA vaccines, while rare clotting syndromes were linked to adenovirus-based vaccines like AstraZeneca.
However, the researchers emphasize that these events were very rare and generally occurred shortly after vaccination, not over long-term periods. When compared with the risks posed by COVID-19 infection itself, the contrast is striking.
COVID-19 Infection Poses a Far Greater Risk
If the vaccine results were surprising to some, the data on infection risk was not. Contracting COVID-19 continues to be associated with a significantly elevated risk of blood clots, strokes, heart attacks, and other serious cardiovascular complications.
For unvaccinated individuals, the inflammatory response triggered by the virus can be far more severe and damaging than anything observed with vaccines. The study reinforces what many scientists and public health experts have warned since 2020: preventing infection—or at least reducing its severity—is one of the best ways to avoid long-term heart and vascular problems.
Experts Respond: A Turning Point for Public Understanding
Co-author Dr. Samantha Ip highlighted the importance of the findings, noting that the scale and depth of the data offer some of the most reliable evidence available about long-term vaccine safety.
She explained that the results should reassure anyone concerned about persistent misinformation, and that understanding the true effects of the vaccines is crucial as the world continues to live with COVID-19.
The study’s conclusions add to a growing list of peer-reviewed research showing that the benefits of vaccination—lower hospitalization rates, reduced risk of severe disease, and now potential cardiovascular protection—far outweigh the rare and mostly short-lived risks.
Why This Study Matters Now
Even though the world has moved beyond the emergency phase of the pandemic, misinformation about vaccine safety remains widespread. Social media posts and misleading commentary continue to shape public perception, often without any supporting scientific evidence.
This study stands out because of its massive scale, rigorous methodology, and transparent acknowledgment of both benefits and risks. For many, it could help rebuild trust and provide clarity at a time when clear, factual information is more important than ever.
A Clear Message: Vaccines Save Lives in More Ways Than One
The research ultimately delivers a compelling message: COVID-19 vaccines do more than protect against the virus itself—they may also reduce the risk of some of the most dangerous cardiovascular emergencies. As health experts continue to encourage vaccination for vulnerable groups, evidence like this strengthens the case for staying up to date with recommended doses.
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Source:
Ip, S., et al. COVID-19 vaccination and risk of arterial and venous thrombotic events in 45.7 million adults. Nature Communications.