Covid vaccines linked to lower risk of heart attacks and strokes, finds large US study

A large US study has found that people who received the latest COVID-19 vaccine shot (2024-2025) alongside their flu shot were less likely to suffer heart attacks, strokes or die from cardiovascular causes than those who did not take the shot. The findings, published in JAMA Internal Medicine, add to evidence that COVID-19 vaccination does not increase the risk of heart problems — a concern that has persisted on social media despite a lack of scientific evidence.

However, experts caution that the results do not necessarily translate into a need for additional vaccine doses in India, where COVID-19 complications are now uncommon and vaccine strategies differ from those in the US.

COVID-19 vaccines have previously been shown to reduce the risk of major adverse cardiovascular events (MACE).

What was the study about?

The cohort study analysed 1,039,659 participants from the US Department of Veterans Affairs between September and December 2024. Researchers compared people who received both the influenza and COVID-19 vaccines with those who received only the influenza vaccine.

At eight months of follow-up, the vaccinated group showed a lower risk of COVID-19-associated MACE, according to lead author Dr Miao Cai, a biostatistician who studies the long-term effects of COVID-19 and vaccine effectiveness.

Because the study was observational rather than a randomised trial, the findings cannot establish cause and effect. The benefit was modest, translating to roughly 2-5 fewer cardiovascular events per 10,000 people.

According to Dr Rajeev Jayadevan, co-chairman of the National IMA Covid Task Force, who was not involved in the study, the reduction in risk was mainly seen among older adults and those with existing health conditions. “The most plausible explanation is that vaccination reduces COVID-19 infections and the blood vessel inflammation that can follow infection, thereby lowering the risk of cardiovascular complications,” he said.

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What the study means for India

India administered more than 2.2 billion doses of COVID-19 vaccines by October 2022, according to the National Health Mission. As vaccine uptake declined, private hospitals gradually reduced procurement.

Even so, public debate over sudden deaths among younger people has frequently centred on concerns about vaccine-related effects. Multiple investigations by Indian agencies, including the Indian Council of Medical Research and the National Centre for Disease Control, have found that COVID-19 vaccines used in India are safe and effective, with serious adverse events being extremely rare.

Experts have pointed out that sudden cardiac deaths can result from a range of factors, including genetics, lifestyle, pre-existing illnesses and complications following COVID-19 infection.

No case for policy change

Dr Jayadevan said the findings should not be interpreted as a basis for changing India’s vaccination policy. “Continued doses of vaccines of the type studied are not being administered as part of India’s programme. Moreover, mRNA vaccines were not used in India unlike in the US. COVID-related complications are now exceptionally rare compared with the earlier phase of the pandemic. Therefore, the study does not support a policy change at this time,” he said.

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At the same time, he said, the findings are reassuring because they counter the false social media narrative that COVID-19 vaccines increase the risk of heart attacks.

India already faces high heart disease burden

India already carries a disproportionately high burden of cardiovascular disease (CVD), particularly among younger adults, said Dr Shrikanth N. Hegde of Anushri Medical and Diabetes Care Centre, Shivamogga, writing in the Association of Physicians of India – Karnataka Journal of Internal Medicine.

India accounts for nearly one-fifth of global cardiovascular deaths, with an age-standardised CVD mortality rate of 272 per 100,000 population, higher than the global average of 235 per 100,000. Coronary artery disease affects an estimated 12-16% of Indians aged 35-65 years and tends to develop 5-10 years earlier than in many other populations.

Among people younger than 45 years, sudden deaths increased from 20,179 in 2019 to 29,147 in 2023, accounting for nearly 46% of all sudden deaths in 2023.