Covid-19 vaccines and sudden heart attacks: Why are experts divided over ICMR study?

While most experts lauded the ICMR initiative, they also called for a comprehensive relook into sudden deaths in Covid-19 vaccine recipients.

ByChetana Belagere

Published Dec 04, 2023 | 9:00 AMUpdatedDec 04, 2023 | 9:15 AM

The researchers failed to differentiate the two Covid-19 vaccines used in India.

Health experts are divided over an Indian Council for Medical Research (ICMR) study that dispelled doubts over the alleged link between Covid-19 vaccines and sudden deaths or heart attacks.

Soon after the study result was published, many called it a “convenient” way for the ICMR — one of the oldest and largest medical research bodies in the world — to dismiss the argument, that vaccines indeed contributed to heart attacks, by attributing the condition to habits such as smoking, alcoholism, or even a sedentary lifestyle, which many Indians have.

A few others spoke about the need for randomised controlled trials — and not case-control study that has been done.

South First spoke to a few experts to understand their views on the methodology and findings of the ICMR study.

On combining vaccines

Noted virologist Prof Jacob John of the Christian Medical College at Vellore in Tamil Nadu praised the study methodology, terming it “remarkable”. He particularly noted its comprehensive and meticulous approach.

However, he also pointed out a significant oversight of the researchers: The failure to differentiate between the two Covid-19 vaccines used in India.

John felt there was a big elephant in the room that the study’s 47 investigators had failed to see.

He explained that one Covid-19 vaccine used in India worked by inducing immunity through a “homemade” spike protein generated in the host’s body, similar to the mechanism employed by the virus itself. This vaccine, Covishield by Oxford-AstraZeneca, was more likely to cause serious adverse events.

On the other hand, the second type of vaccine, Covaxin by Bharat Biotech, used an inactivated virus, a method he lauded as an “Indian contribution to vaccinology”.

John emphasised that these two vaccines could not be grouped due to significant differences in their safety profiles. He argued that without a sub-analysis detailing the number of people vaccinated with these two drugs, it would be impossible to accurately assess the risks.

The virologist stated that the inactivated-virus vaccine had never been linked to serious adverse events, such as heart attacks, neurological problems, bleeding, or clotting. Conversely, the other vaccine had been alleged to cause such issues, although this was not definitively known.

“This distinction is crucial,” John argued, because clubbing both vaccines under the general category of “Covid vaccines” was a major flaw in the study.

He asked whether a single dose of the safer vaccine (likely the inactivated-virus vaccine) would show a reduced risk of sudden death, as opposed to the other vaccine, which might have a small but notable risk.

John called for more nuanced analysis and reporting, especially considering the impact of each vaccine on sudden-death risk.

Without such differentiation, he believed that any conclusions drawn about the safety of “Covid vaccines” as a whole would be misleading and potentially harmful.

Related: Lifestyle cause of sudden surge in young-adult deaths, says study

Need for a relook

Dr KR Antony, a paediatrician and public health consultant based in Kochi in Kerala, raised significant concerns about the study’s methodology and conclusions in a detailed conversation with South First.

He noted that the ICMR study looked at 29,171 sudden deaths in the 18-45 age group, allegedly related to Covid-19 vaccination, reported through 47 tertiary-care hospitals.

The first question that a researcher should have looked into was if such a level of incidence was a normal pattern in the previous years and seasons, he said.

Antony felt the study failed to establish whether there was a direct causal relationship between the vaccination and subsequent cardiac events or strokes. There were established methodologies for causality analysis, designed by WHO, on adverse events following Immunisations, he said.

Instead, the team investigated the significance of some factors associated with the 729 victims and 2,916 peers of similar age groups in the community.

He pointed out that the study excluded histopathological (tissue-diagnosis) examinations of organs of individuals who succumbed post-vaccination, a critical factor in determining the actual cause of death.

Whatever deaths in which post-mortem examinations were done, extraction of that information and summation of those findings would have enriched the ICMR study, he said.

Following Covid-19 hospitalisation, the family history of sudden-death individuals, binge drinking 48 hours before death, use of recreational drugs/substances and performing vigorous-intensity physical activity 48 hours before death were positively associated, the study claimed. Also, receiving two doses of the Covid-19 vaccine reduced death risks.

“The method of just comparing six associated factors between vaccinated and unvaccinated individuals without a histopathological report of victims is flawed,” Antony argued. In a statistical jugglery, what was hidden was more important than those revealed to know the truth.

Interview: Dr Gagandeep Kang’s take: ICMR has done best it could

Importance of histopathology

He emphasised the need to include post-mortem histopathology reports to accurately determine vaccine-related complications.

He stressed the importance of a time relationship with the development of complications, management interventions made but did not succeed in such deaths, and any post-mortem that was done.

Many post-mortem examinations were inadequate, and conducted without the necessary medical college faculties or experts in histopathology.

Antony noted that Covid-19 vaccines, depending on their platform of manufacturing, could induce an exaggerated immune response leading to hyperinflammatory reactions and clotting.

Explaining, he said, there was a difference in clot characteristics in typical myocardial infarctions and stroke compared to those found after Covid-19 vaccinations, which were diffused microclots. Only a histopathologist could differentiate it. Such experts must be available in the 47 study centres.

Antony also pointed to the European Union’s decision to ban certain Covid-19 vaccines based on the deaths among youth after vaccination. Against this backdrop, he urged for honest reporting and investigation into vaccine-related deaths, crucial for public health transparency and scientific integrity.

He advocated a more rigorous approach by the ICMR and related agencies to win the confidence and appreciation of the scientific community. He called for a reassessment of the study methodology and a commitment to scientific honesty in reporting vaccine-related incidents. He was sceptical about the general dismissal of vaccine-related incidents as coincidental.

Related: Delhi study says no proof of Covid shots hiking heart-attack risk

In defence of the study

However, noted microbiologist Dr Gagandeep Kang and Dr Rajeev Jayadevan — the latter was part of the Covid-19 task force in Kerala and also the former president of the IMA’s Kochi chapter — praised the ICMR study.

Kang acknowledged the inherent difficulties in drawing concrete conclusions from the available data. “Answering these questions post-factum with incomplete data is a challenging task,” she stated.

In an ideal scenario, comprehensive clinical records documenting vaccination timelines, illness onset, and lifestyle factors would enable more accurate analyses. However, she noted that such detailed data was rarely available in India.

Despite the limitations, Kang lauded the ICMR for its efforts. She suggested that if there were a significantly strong correlation between vaccination and subsequent health events, it would likely have been detected in the study. The subtlety, she explained, was in identifying rare associations, which could be incredibly challenging with incomplete data.

Dr Kang emphasised the importance of continuous inquiry and improvement in scientific research. “If there are doubts about the study’s findings, the onus is on the scientific community to strive for better data and analysis,” she said.

Voicing a similar opinion, Dr Jayadevan noted that the researchers followed a robust methodological framework, typical of such epidemiological studies. He cautioned against dismissing the study’s findings without a sound understanding of its methodological foundations.

Dr Jayadevan emphasised the complexity of establishing causality in such cases. He pointed out that many critics of the study might lack a deep understanding of epidemiological research methods. “In the modern pandemic era, we encounter numerous pseudo-experts who grasp a few keywords but fail to understand the intricacies of study designs,” he said.

On the difficulty in determining the cause of sudden deaths. Dr Jayadevan explained that even autopsies, often seen as definitive, need not always reveal the exact cause, especially in cases like arrhythmias (irregular heartbeat), which would leave no physical trace. He defended the case-control study approach used in the research.

The method, he argued, was standard for investigating rare outcomes from common exposures. He stressed that the study’s methodology, involving comparing the vaccinated individuals with a control group, was a valid approach to understanding potential vaccine side effects. However, Dr Jayadevan acknowledged that improvements were always possible in scientific research.

Meanwhile, several social media handles, too, have questioned the ICMR study. Venugopalan Govidan, who identified himself as “An idiot who vaccinated his daughter w/o studying about adverse effects and lost her,” wrote about the ICMR study on his daughter’s handle on X.

“ICMR has conflicts of interest. In fact, much more than monetary interest they had survival at stake and finding a causality of vaccine would have exposed them and threatened their existence. Reports outcome was predetermined.”

Against the backdrop of questions galore on the vaccines, the experts’ call for a more comprehensive study gains importance.