A study by the US health regulator FDA, which shows an increased risk of heart disease after Covid-19 mRNA vaccination, has caused a buzz about vaccination protocols. And though India uses replicating vector vaccines such as Covishield and the inactivated-pathogen-based Covaxin, concerns arise as it is also in the process of rolling out its own mRNA vaccine.
The study, which was published in the peer-reviewed medical journal, The Lancet, shows an increased risk of myocarditis or pericarditis, particularly among young men between 18 and 25 years, after mRNA vaccination. Myocarditis is inflammation of the heart muscle and pericarditis is inflammation of the outer lining of the heart. However, the study clarifies that the incidence is “rare”.
Prof Gagandeep Kang, Gastrointestinal Sciences, Christian Medical College, Vellore, and one of India’s most trusted virologists, said: “This risk was first identified in Israel a year ago. The condition is rare, mostly mild, and affected people recover. The important thing with every vaccine is that when there is a known side-effect, people should be educated so that they can recognise and report the condition when it occurs and receive appropriate advice and management.”
Globally, mRNA vaccines have driven inoculation programmes in the United States and Europe because they took advantage of recent advancements in molecular biotechnology to roll them out quicker. Explaining the study, Dr Chandrakant Lahariya, physician-epidemiologist and vaccines expert, said, “The Lancet study validates what we knew for a while. The increased risk of myocarditis and pericarditis after mRNA vaccines in older children and young adults has been documented and reported since these vaccines began to be rolled out. What we know is that this risk is inversely proportional to the age of the vaccine recipient. The study has been conducted on an adult population and found this increased risk is almost similar for both currently authorised mRNA vaccines. Not part of The Lancet study, but it has been documented that adolescents have a higher risk than even young adults of 18-25.”
Asked about other vaccines, Dr Lahariya said: “The other vaccines, specially the viral-vectored vaccines, like the Oxford-AstraZeneca (Covishield in India) had been found to be associated with increased risk of blood clotting in younger age groups. This is the reason why many countries, which gave emergency authorisation to the Oxford-AstraZeneca vaccine, are not using it for their below-30 population. It is not approved for children younger than 18 years.”
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Ruling out panic, he explained, “We need to remember that regulatory bodies approve the vaccines based upon their safety profile. They are made as safe as possible. However, rare adverse events are possible, as we are learning about various Covid-19 vaccines. Their use is also determined by the balance of benefit versus risk. If benefits of administering the vaccine in preventing disease are considered high and risk lower, those are recommended. All regulatory bodies follow this approach and we know the benefit of currently-licensed Covid-19 vaccines is far greater and the risk is acceptable. However, such safety data is very useful for governments to design and select appropriate vaccines for different age groups and also to determine whether to vaccinate a certain age group or not. Second, such safety data allows vaccine manufacturers and researchers to identify mechanisms and reduce the risk of adverse events.”
According to him, the risk of pericarditis and myocarditis has also been found “in Novavax, which is approved as Covovax in India. So, the risk is not exclusively for mRNA vaccine-linked adverse events.”
“Occurrence of pericarditis and myocarditis in young men receiving mRNA vaccines was first reported from Israel and later confirmed in the US and Europe. American athletes, who were screened for heart muscle function after Covid-19 vaccination, exhibited these effects but recovered without lasting effects. There is concern about repeating mRNA vaccines as boosters in this age group of males, though the overall risk is judged to be low. It is safer to use non-mRNA vaccines, especially subunit protein vaccines, as boosters for this population group. India has not used mRNA vaccines and has not witnessed this adverse effect,” said Dr Srinath Reddy, president, Public Health Foundation of India and former head of department of cardiology at AIIMS.
Dr Sanjeev Jadhav, chief cardiothoracic surgeon and director of heart and lung transplant, Apollo Hospital, Mumbai, would much rather concern himself with the Indian context. “From an Indian perspective, most have received Covishield and Covaxin and we have seen other types of complications in a sub-set, mainly thrombo-embolism vessels producing clots in heart or peripheral vessels and migrating to lungs. Pulmonary thrombo-embolism is more common in our sub-set – yet there is a long way to go and understand what happens and what is the molecular biology knowledge to be acquired about the clinical situation regarding the mRNA vaccine,” he said.
However, the US FDA study, along with the benefit-risk profile, continues to support inoculation using either of the two mRNA vaccines. India’s own mRNA vaccine, supported by the Department of Biotechnology (DBT), is being keenly studied by drug regulatory authorities. This mRNA vaccine, its makers claim, can also purportedly be tweaked to be effective against newer variants.