- Recent studies have suggested that COVID-19 vaccines may increase the risk of heart inflammation, which can be potentially fatal.
- A meta-analysis synthesizing data from 22 previous studies suggests that the risk of heart inflammation following a COVID-19 vaccine was similar to the risk after vaccination against other diseases.
- Men and people under the age of 30 had a higher risk of heart inflammation, especially after the second dose.
- These results suggest that the risk of heart inflammation after receiving a COVID-19 vaccine is generally low, supporting previous data on their safety.
A meta-analysis published in
However, the results of the study suggest that being of the male sex and being younger were associated with an increased risk of heart inflammation following a COVID-19 vaccine. These results could inform public policy decisions on vaccination protocols to reduce the risk of heart inflammation in these demographic conditions.
The co-author of the study, Dr.Kollengode Ramanathana cardiologist at the National University of Singapore, says:
“Our research suggests that the overall risk of myopericarditis (inflammation of the heart) does not appear to be different for this newly approved group of COVID-19 vaccines compared to vaccines against other diseases.”
“The risk of such rare events should be weighed against the risk of myopericarditis from infection, and these findings should strengthen public confidence in the safety of COVID-19 vaccinations,” Drs. Ramanathan.
Myocarditis is a medical condition that involves inflammation of the heart muscle, while pericarditis is inflammation of the membrane or mucous membrane that surrounds the heart. Myocarditis and pericarditis can also occur simultaneously, and this condition is known as
One of the common causes of myocarditis includes viral infections. For example, surveys (
In most cases, myocarditis following a SARS-CoV-2 infection is short-lived and resolves on its own. However, in rare cases, myocarditis can lead to permanent heart damage, heart failure and death.
In addition, some studies have suggested an association between COVID-19 vaccination and an increased risk of myopericarditis, particularly among younger men.
However, some of these studies of the negative effects of vaccination were based on self-reports that are sensitive to bias. In addition, improvements in post-vaccination adverse reaction reporting have made it difficult to assess whether the risk of myopericarditis after receiving a COVID-19 vaccine is higher than other vaccines.
To address these issues, this study compared the incidence of myopericarditis after receiving a dose of a COVID-19 vaccine with that after non-COVID-19 vaccinations.
The study also assessed the impact of age, sex, dose and type of COVID-19 vaccine on the risk of myopericarditis following COVID-19 vaccination.
In this study, the researchers analyzed data on over 400 million vaccine doses accumulated from 22 studies that assessed the incidence of myopericarditis after receiving a vaccine.
Specifically, the analysis included 11 studies involving over 395 million COVID-19 vaccine doses. The remaining studies involved non-COVID-19 vaccines, including smallpox vaccines (6 studies) and influenza vaccines (2 studies).
The researchers found that the incidence of myopericarditis after a dose of a COVID-19 vaccine was not higher than the estimated rates of the condition in the general population before the COVID-19 pandemic.
In addition, the incidence of myopericarditis after receiving a dose of the COVID-19 vaccine was comparable to that after immunization with a non-COVID-19 vaccine. The smallpox vaccine was an exception to this trend with a higher incidence of myopericarditis after a smallpox vaccine than after a COVID-19 vaccine.
The authors of the study also noted that the incidence of myopericarditis after COVID-19 vaccination appears to be lower than previously reported estimates of myopericarditis after a SARS-CoV-2 infection.
The researchers then assessed the effect of the type of COVID-19 vaccine, age and sex on susceptibility to myopericarditis after receiving a COVID-19 vaccine.
They found that the number of myopericarditis cases after an mRNA COVID-19 vaccine was almost three times higher than after a dose of a non-mRNA COVID-19 vaccine.
In addition, the risk of myocarditis was higher after the second dose of a COVID-19 vaccine than the first or third dose.
Myopericarditis after receiving a dose of a COVID-19 vaccine was also more common in men than in women and in individuals under 30 years of age than in persons aged 30 years and over.
In particular, the incidence of myopericarditis in men younger than 30 was ten times higher than in women in the same age group.
“Analyzes of the pathology and immunological mechanisms behind these demographically dependent adverse reactions after vaccination are likely to advance our understanding of cardiology and immunology. These advances could spur the development of safer vaccines or precision vaccination practices.”
The study authors acknowledged that their study had a few limitations.
Dr. Ramanathan told MNT:
“Our results cannot be generalized to children younger than 12 years of age as there were limited data reported on this age group. The comparisons between COVID-19 and non-COVID-19 vaccines were also made across different time periods.”
“Developments in tools (MRI, widespread echocardiography, biopsy) and improvements in vaccine monitoring systems may introduce heterogeneity and reporting in the treatment of myopericarditis,” he added.
Dr. Anders Husby, told a postdoctoral fellow at the Statens Serum Institut, Denmark, who was not involved in the research MNT“The study is limited by the relatively few and mostly small studies of myocarditis after non-COVID-19 vaccines, making it difficult to determine the extent of the effects of non-COVID-19 vaccines.”