COVID-19 vaccine
COVID-19 vaccineOlivier Fitoussi/Flash 90

A joint study by the Cardiology Department at Beilinson Hospital and the Clalit Research Institute has found that myocarditis after a COVID-19 vaccine is rare even in the group at highest risk: young men.

The results of the study, published on Wednesday in the New England Journal of Medicine, show that in the vast majority of cases the disease was mild, and no significant effects on cardiac functionality were found.

The study is based on an anonymous data analysis of 2.5 million Clalit patients who received the Pfizer vaccine against COVID-19, 94% of whom received two vaccine doses. The aim of the study was to characterize cases of myocarditis after vaccination against the virus.

The study found that out of 2.5 million people from the age of 16 who received the vaccine, 54 patients with myocarditis were detected within a period of up to 42 days after receiving the vaccine, 51 of them men and three of them women. This is 2.13 cases for every 100,000 people vaccinated. The data also showed that the side effect appeared more after the second vaccine dose (69%) than the first, more in men than women, and more in the 16-29 age group compared to those vaccinated over the age of 30.

Myocarditis in the group with the highest prevalence - men aged 16-29, reached 10.7 cases per 100,000 vaccinated. The data also showed that a total of 76% of cases of myocarditis were described as mild and 22% as intermediate; one case was associated with cardiogenic shock.

The researchers stressed that most patients (71%) had no signs of impaired cardiac function at any stage.

Professor Ran Kornowski, Director of the Cardiology Center at Beilinson Hospital, noted that these are significant results and that researchers hope they will enable informed decisions about the enormous and proven benefit of the vaccine's high efficacy.