Israel's Health Ministry said on Tuesday it had found the small number of heart inflammation cases observed mainly in young men who received Pfizer's Covid-19 vaccine in Israel were likely linked to their vaccination.
Pfizer has said it has not observed a higher rate of the condition, known as myocarditis, than would normally be expected in the general population.
In Israel, 275 cases of myocarditis were reported between December 2020 and May 2021 among more than 5 million vaccinated people, the ministry said in disclosing the findings of a study it commissioned to examine the matter.
Most patients who experienced heart inflammation spent no more than four days in the hospital and 95% of the cases were classified as mild, according to the study, which the ministry said was conducted by three teams of experts.
The study found "there is a probable link between receiving the second dose (of Pfizer) vaccine and the appearance of myocarditis among men aged 16 to 30," it said in a statement. According to the findings, such a link was observed more among men aged 16 to 19 than in other age groups.
The European Medicines Agency (EMA) said last week that heart inflammation following vaccination with Comirnaty had been no cause for concern as they continued to happen at a rate that typically affected the general population. It added at the time that young men were particularly prone to the condition.
A U.S. Centers for Disease Control and Prevention advisory group last month recommended further study of the possibility of a link between myocarditis and mRNA vaccines, which include those from Pfizer and Moderna Inc.