In a recent study published in The Lancet Respiratory Medicine journal, researchers investigated the impact of coronavirus disease 2019 (COVID-19) vaccination on the incidence of myopericarditis.
Studies have reported several cases of myopericarditis after COVID-19 vaccination in adolescents and young adults. However, there is insufficient knowledge regarding the mechanism of pathogenesis of myopericarditis post-COVID-19 vaccination.
About the study
In the present meta-analysis, the researchers compared the presentation of myopericarditis after COVID-19 vaccination to that after vaccination against other diseases such as influenza, smallpox, and mixed infections. The study also estimated the incidence of myocarditis and pericarditis and the related mortality rates post-vaccination.
The team searched databases including MEDLINE, Pubmed, Embase, Cochrane, and Scopus for relevant studies and collected data using a prespecified data extraction form. They also evaluated the number of patients suffering from myopericarditis, the total number of vaccines administered, and the related incidence rate.
The team defined myopericarditis as an umbrella term that described myocarditis and/or pericarditis. Furthermore, the overall certainty of the evidence was calculated via the Grading of Recommendations, Assessment, Development, And Evaluations (GRADE) approach.
The researchers examined the difference in the incidence of myopericarditis among subpopulations that were prespecified based on the type of vaccine administered, which were either COVID-19 or non-COVID-19 vaccines such as influenza and smallpox vaccines, either messenger ribonucleic acid (mRNA) COVID-19 or non-mRNA COVID-19 vaccines, and the age group, which was divided into the pediatric or adult population.
Furthermore, the incidence of myopericarditis was compared based on gender and the number of COVID-19 vaccine doses administered.
The primary outcome of the study was the incidence of myopericarditis following any vaccination, while the secondary outcomes were the incidences of myocarditis and pericarditis and the related mortality rates after any vaccination.
A total of 156 full-text publications and 22 observational studies were analyzed, which included 4,05,272,721 vaccine doses. Among the studies, 11 reported 3,95,361,933 doses of COVID-19 vaccines, six reported 2,900,274 doses of smallpox vaccines, two reported 1,521,782 doses of influenza vaccines, and three reported other non-COVID-19 vaccines. Out of the nine studies that described the type of COVID-19 vaccines, 2,90,730,653 and 51,969,677 doses were of mRNA and non-mRNA vaccines, respectively.
The team reported an overall myopericarditis incidence of 33.3 cases per million vaccine doses. The overall incidence of myopericarditis did not substantially differ after the administration of COVID-19 vaccines compared to non-COVID-19 vaccines.
However, a comparison of the COVID-19 vaccine with each non-COVID-19 vaccine showed a remarkable difference between different subpopulations. The incidence of myopericarditis was 1.3 per million doses of influenza vaccine, 132.1 per million doses of smallpox vaccine, and 57 per million doses of other non-COVID-19 vaccines.
The incidence of myopericarditis did not significantly differ between adults (aged 18 years and above) and pediatric populations. However, substantially higher myopericarditis incidence was observed in mRNA vaccinees compared to non-mRNA vaccinees. Furthermore, among COVID-19-vaccinees, males aged below and above 30 years had a 10-fold and three-fold higher susceptibility to myopericarditis, respectively, than females aged above 30 years. Additionally, doubly vaccinated individuals showed a higher incidence of myopericarditis than those who were singly vaccinated.
Furthermore, the study found that age was negatively correlated to the incidence of myopericarditis in COVID-19 vaccinees. In addition, the incidence of myopericarditis was 16 cases per million doses of any vaccine. Altogether, the likelihood of myopericarditis incidence was lower in COVID-19 vaccinees than in non-COVID-19 vaccinees.
To summarize, the study findings showed that the overall incidence of myopericarditis after receiving COVID-19 vaccines was similar to that after influenza vaccination and lower than that after smallpox vaccination.
The researchers believe that the individual decision to receive the COVID-19 vaccine should be made after considering both the benefits and harm associated with the vaccine.