Are COVID vaccines responsible for sudden deaths? 

There is no scientific evidence linking COVID vaccines to sudden deaths. On the contrary, COVID-19 disease itself poses a significant cardiovascular risk, even years after apparent recovery. Studies have shown that those who received COVID vaccine are at lower risk of subsequent cardiovascular events and deaths. COVID-19 death toll is estimated at seven million, the true numbers could be several-fold higher. Without vaccines, the number of deaths would be much greater. 

Sudden deaths, particularly among young adults, have long been a subject of medical research. While such deaths have always been occurring, the recent rise of social media and easy availability of video recordings have amplified their visibility. This has led to a growing public perception that sudden deaths among young people are increasing. However, it is essential that our understanding of this issue is grounded in scientific data and peer-reviewed literature — not speculation or viral narratives.

What do the numbers say?

A landmark Indian study published in 2011, which tracked several thousands of individuals across multiple villages, found that the annual risk of death from heart attacks in men aged 35 to 45 was approximately 1 in 1,700. India is a young nation, with a median age of 28.6 years. This means a large proportion of the population is relatively young compared to Western countries. As per a February 2023 study in the journal Lancet Regional Health Southeast Asia, cardiovascular burden in India is higher than the global level. While the age-standardised death rate level globally is 233 deaths per 1,00,000, for India it is 282 deaths per 1,00,000.

Consequently, the average age of a heart attack in India is in the early 50s, significantly lower than in western countries. However, this average is skewed by India’s demographic pyramid, where younger age groups dominate in number, pulling the average age downward. This also reflects the uncomfortable reality: many individuals below the age of 50 do suffer heart attacks — some of which are fatal.

There are 10 established coronary risk factors — age, gender, smoking, diabetes, hypertension, high LDL cholesterol, poor diet, sedentary lifestyle, obesity, and family history of premature heart disease. Additional risk factors include air pollution, binge drinking and sleep disorders. Viral infections such as influenza are also linked with increased heart attack risk. Many of these are modifiable risk factors, and early adoption of a healthy lifestyle can reduce one’s risk. 

Since the COVID-19 pandemic, an additional risk factor has emerged. Multiple studies have shown that individuals who recover from COVID-19 experience elevated long-term cardiovascular risk, compared with those who were never infected. For example, a large UK Biobank study, done before the arrival of vaccines and involving over half a million adults, found that COVID-19 survivors had double the risk of cardiovascular events in the three years following initial infection. Among those hospitalised with severe COVID, the subsequent risk was four-fold.

A U.S. study published in Nature Medicine (2022), found that the risk and burden of cardiovascular disease one year after recovering from COVID-19 disease was “substantial”. Also, the risks and burden of cardiovascular disease were present even among individuals with mild infection that did not require hospitalisation. Most importantly, the study found that 30 days after infection, individuals with COVID-19 were at “increased risk of incident cardiovascular disease” across several categories — cerebrovascular disorders, dysrhythmias, ischemic and non-ischemic heart disease, pericarditis, myocarditis, heart failure and thromboembolic disease. 

A more recent large study in Scientific Reports published in December 2024 involving over 56,000 people with COVID-19 and over one million controls confirms that this heightened risk persists for up to 3.5 years post-infection.

Importantly, these studies excluded individuals who experienced cardiovascular events during or immediately after COVID-19, suggesting that even after clinical recovery, the body may carry lingering vulnerability and inflammation. A likely reason is that the SARS-CoV-2 virus attacks the inner lining of arteries called endothelium, which has an important role in cardiovascular health.

The role of vaccination

Contrary to popular belief and widespread misinformation, COVID-19 vaccination is not linked to sudden deaths. In fact, research indicates the opposite. A Swedish study published in September 2024 in the European Heart Journal found that individuals who were fully vaccinated had “substantially reduced risk of several severe COVID-19-associated cardiovascular outcomes”, highlighting the protective benefits of COVID vaccination. 

A major study carried by the Chennai-based ICMR institution — National Institute of Epidemiology (ICMR-NIE) — across 48 centres in India between October 2021 and March 2023 and published in the Indian Journal of Public Health (2023) examined 729 cases of sudden deaths, including sudden cardiac deaths, in people aged 18-45 years. The researchers compared the cases with nearly 3,000 healthy individuals who were matched for age, gender, and location. 

Sudden deaths were not found associated with COVID-19 vaccines but were instead associated with binge drinking, recreational drug use, family history of premature heart disease, history of COVID-related hospitalisation, and intense physical exertion immediately following COVID-19. The study concluded that there was no increased risk of sudden death associated with receiving COVID-19 vaccine. In fact, those who received two doses of vaccine were less likely to experience sudden death, indicating vaccines were protective.

Safety profile of COVID-19 vaccines

India primarily used two types of vaccines — Covishield, which is an adenovirus vector vaccine, and Covaxin, an inactivated virus vaccine. Covishield made up about 85-90% of India’s COVID‑19 vaccinations, with Covaxin accounting for around 10-15%. Both these vaccines were put through clinical trial phases before approval. The aim of the phase-3 clinical trials is to determine the vaccine’s efficacy in preventing COVID-19 compared to those who did not receive it, and to assess safety in a large number of participants. 

Unlike trials for rare diseases like polio and smallpox — which took years to complete due to low case numbers — the rapid spread of COVID-19 in large groups of people allowed vaccine trials to reach the required statistical endpoints quickly. This has been misinterpreted by anti-science activists, claiming that “vaccines were rushed without clinical trials”. Since the vaccines were tested during a fast-spreading pandemic, long-term follow-up for safety was not feasible before authorisation. That being said, very rare adverse events such as VITT — occurring in only 1 in 50,000 cases — could easily be missed even in large trials involving 26,000 participants even with a year-long follow-up.

While it is true that Covaxin was approved in the absence of published phase-3 trial results, that was also the norm in countries including China and Russia where several vaccines were deployed as an emergency measure before trials were concluded. These vaccines were also accepted for use in multiple countries. In contrast, the COVID vaccine by AstraZeneca and the two mRNA vaccines were authorised for emergency use by the respective drug regulators only after results of a phase-3 trial were available. Waiting for more months would have cost many people their lives, this indeed is the basis of Emergency Use Authorisation (EUA).

The first interim analysis for Covaxin in early March 2021 showed the vaccine to be safe, with 81% efficacy. This was based on 25,800 participants, in whom 36 Covid-19 cases had occurred in the placebo group and only seven occurred in the vaccine group. At the time of interim analysis on May 17, 2021, 130 COVID-19 cases had accumulated among the study participants, confirming the early results. 

Unverified claims on social media linking vaccines to sudden deaths have fueled widespread vaccine hesitancy — with serious public health consequences. In parts of India, vaccine uptake has declined significantly due to such fears. Diseases once under control, like measles, are making a comeback, as seen in the U.S. These trends underscore the real-world danger of spreading misinformation about vaccines.

Controversial statements

Recent statements on X (formerly Twitter) by Karnataka Chief Minister Siddaramaiah — suggesting that “hasty approval and distribution” of COVID-19 vaccines may be responsible for over 20 apparent heart attack deaths in Hassan district, and citing unspecified global studies linking vaccines to increased heart attacks — are not supported by scientific evidence. In fact, published data consistently show the opposite: COVID-19 vaccination is associated with a reduction in cardiovascular deaths.

At this point, it is unclear whether those who died in Hassan had any recent illnesses or toxic exposures, a history of severe COVID-19 or prior asymptomatic SARS-CoV-2 infection, comorbidities or family history of premature heart disease, and have been fully vaccinated or even vaccinated at all. There is also no information about their clinical course, lifestyle factors, or whether they had previously required hospitalisation for COVID-related complications.

Most importantly, an isolated cluster of sudden deaths in a single district cannot logically or scientifically be attributed to vaccines that were administered over three years ago to millions across the country. If COVID-19 vaccines were indeed causing fatal heart events, we would have seen a widespread and consistent spike in such deaths nationwide — which has not occurred.

While it is important to call for an investigation, making controversial speculations based on popular public opinion goes against scientific temperament. Such statements can undermine public trust and fuel antivaccine sentiments, leading to far-reaching consequences — where dangerous diseases once controlled with vaccines experience a resurgence. 

Serious adverse events

Like other vaccines, COVID-19 vaccines stimulate the immune system to generate protection without subjecting the person to the risk of an actual infection. This immune response may cause temporary symptoms like fever, body aches, and local pain at the injection site. These are well-documented and expected side effects, with significant variation between individuals.

The mRNA vaccines used widely in western countries carry a small risk (1 in 37,000-1,25,000) of myocarditis or pericarditis, particularly in young males. These cases typically occur within a month of vaccination, and nearly always resolve completely. Unlike the U.S., vaccines used in India have considerably lower risk of myocarditis. Adenovirus vector vaccines used in India and other countries were later found to carry a very rare risk of vaccine-induced immune thrombotic thrombocytopenia (VITT), a condition involving blood clots with low platelet counts. This occurred in approximately 1 in 50,000-1,00,000 recipients. The majority of VITT cases were non-fatal and occurred within two weeks of the first dose of vaccination — not months or years later. These events were extremely rare, well-documented, and time-limited. Given that mass vaccination happened mainly in 2021 and 2022, there is virtually no possibility that VITT is causing sudden deaths in 2025. Importantly, such rare risks must be weighed against the hundreds of thousands of lives saved by these vaccines during the pandemic.

Sudden death: Not always a heart attack

Social media narratives often equate sudden death with heart attacks or cardiac arrest. But these are distinct entities — 1) sudden death where death occurs within 24 hours, without prior warning, 2) cardiac arrest where the heart stops due to a rhythm disturbance (like ventricular fibrillation), 3) heart attack (myocardial infarction) caused by blockage of blood flow to the heart muscle, which can sometimes lead to cardiac arrest, and 4) myocarditis, which is inflammation of the heart muscle, commonly of viral origin (including COVID-19), in which recovery is the general rule. 

Why do young adults die suddenly?

While sudden death in older adults is most commonly due to heart attacks, the causes in younger individuals are more varied. These include severe infections (such as malaria, meningitis, or pneumonia), pulmonary embolism (a blood clot in the lung), unnoticed snakebites (e.g., from kraits), drug overdose or poisoning, exposure to toxic gases like carbon monoxide or hydrogen sulphide, suicide without overt clues, or intracranial bleeding. In addition to heart attacks, sudden cardiac death in young adults can also result from underlying heart muscle disorders like cardiomyopathy (often genetic), or congenital abnormalities of the heart’s electrical conduction system. Many of these conditions remain clinically silent until a catastrophic event occurs.