A meta-analysis of 23 studies, including 854 patients aged 12 to 20 years with mRNA vaccine-associated myopericarditis (rare acute heart inflammation), has found that the incidence of myopericarditis was higher in males after the second dose, adding that however, the overall cases are very low.

The findings, published in JAMA Pediatrics, a journal of JAMA Network, suggest largely low incidence rates and favourable outcomes of Covid vaccine-associated myopericarditis in adolescents and young adults.

“This systematic review and meta-analysis found low incidence rate and largely favourable early outcomes of Covid-19 mRNA vaccine-associated myopericarditis in adolescents and young adults from a wide range of populations. These findings are reassuring but continued follow-up is warranted,” the researchers noted.

Last month, a study in the Journal of the American College of Cardiology found that the incidence of myocarditis, pericarditis or myopericarditis is two- to threefold higher after a second dose of the Moderna Spikevax Covid-19 vaccine when compared to the Pfizer BioNTech Covid-19 vaccine.

However, “overall cases of heart inflammation with either vaccine are very rare”, it said.

Since the emergency use was authorised, the association of the mRNA-based Covid-19 vaccine with myopericarditis, which is a rare but serious adverse event, has been reported worldwide, especially in adolescents and young adults.

The new JAMA study by Jun Yasuhara of Nationwide Children’s Hospital in Columbus, Ohio, and Toshiki Kuno, of the Albert Einstein College of Medicine in Bronx, New York, found that their findings are consistent with results from previous studies in adults, in which clinical course of Covid-19 vaccine-associated myopericarditis was typically mild, “with complete resolution of symptoms and LV systolic dysfunction at presentation normalised within a few days”.

“Importantly, the risk of developing myocarditis after SARS-CoV-2 infection is significantly higher than after Covid-19 mRNA vaccination,” they noted.

Accordingly, the benefits of the mRNA Covid-19-19 vaccination are deemed to outweigh the potential risks, said the JAMA study.

Despite the lack of severe complications commonly associated with Covid-19 mRNA vaccination, vaccine hesitancy remains high, and some parents still hesitate to vaccinate their children against Covid-19, said the study.