What is myocarditis? A rare complication of COVID-19 and non-Covid vaccinations
A large part of the world's population has received the coronavirus (COVID-19) vaccine, either one or two; some even have been inoculated with the booster shots. More than 10 billion doses of COVID-19 vaccines have been administered globally as of March 2022.
Some people have experienced the side effects of the Covid vaccines, usually mild and self-limiting. Fever, fatigue, headache, muscle pain, chills, diarrhoea and pain at the injection site are some of the common symptoms experienced by most people.
However, a recent report published in The Lancet Respiratory Medicine concluded that some people have experienced severe heart inflammation. It has been described as a rare risk associated with COVID-19 vaccines.
Researchers from National University Hospital, Singapore examined international databases to understand the incidence of myocarditis following COVID-19 vaccination and compare this with non-COVID-19 vaccination as well.
Experts have noted that Myocarditis is an inflammation of the heart muscle (myocardium). The inflammation can reduce the heart's ability to pump and cause rapid or irregular heart rhythms (arrhythmias).
It has also been understood that the term pericarditis refers to inflammation of the pericardium and myocarditis and both can occur together in clinical practice.
The study mentioned that the "overall risk of myopericarditis after receiving a COVID-19 vaccine is low". However, younger males have an increased incidence of myopericarditis, particularly after receiving mRNA vaccines.
Part of the study read, "Nevertheless, the risks of such rare adverse events should be balanced against the risks of COVID-19 infection (including myopericarditis)."
The study was based on a sample size of more than 400M vaccine doses and the overall incidence of myocarditis from 22 studies was 33·3 cases per million vaccine doses.
The study noted that it did not differ significantly between people who received COVID-19 vaccines and those who received non-COVID-19 vaccines.
As rates of myocarditiss were higher in smallpox shots as compared to coronavirus jabs. Whereas it is about the same as in influenza, measles, mumps and rubella and polio vaccines.
"Our research suggests that the overall risk of myopericarditis appears to be no different for this newly approved group of vaccines against Covid- 19, compared to vaccines against other diseases," said Dr. Kollengode Ramanathan, a cardiac intensivist at the Hospital.
"The risk of such rare events should be balanced against the risk of myopericarditis from infection and these findings should bolster public confidence in the safety of Covid-19 vaccinations," Ramanathan added.
"The occurrence of myopericarditis following non-Covid-19 vaccination could suggest that myopericarditis is a side effect of the inflammatory processes induced by any vaccination and is not unique to the SARS-CoV-2 spike proteins in Covid-19 vaccines or infection," said Dr Jyoti Somani, an infectious diseases specialist at the Hospital.
"This also highlights that the risks of such infrequent adverse events should be offset by the benefits of vaccination, which include a lower risk of infection, hospitalisation, severe disease, and death from Covid-19," she added.