There have been recent reports of myocarditis (including myocarditis, pericarditis, or myopericarditis) as a side-effect of some COVID-19 vaccines.  The United States Centers for Disease Control and Prevention (CDC), said on Thursday, Dec 16 that it had received reports of eight cases of myocarditis, a type of heart inflammation, in children aged 5-11 years who received Pfizer and BioNTech’s COVID-19 vaccine.

The CDC had previously said that reporting rates of myocarditis for boys aged 16 to 17 could be more than 69 cases per million-second doses administered and around 40 cases per million-second doses in boys aged 12-15 years old.

The CDC did not say whether it believes there is a link between the myocarditis cases and the vaccine or disclose the rate of myocarditis in the age group without vaccination.

The agency said there had been over 7 million vaccine doses in the 5-11 age group at the time it examined the data, with 5.1 million first doses and 2 million second doses. The cases had a mild clinical course, the CDC said.

The cases were reported in the US Vaccine Adverse Event Reporting System and presented by the CDC to a panel of its expert advisers.

According to an article posted on medrxiv.org, Myocarditis (or pericarditis or myopericarditis) from primary COVID19 infection occurred at a rate as high as 450 per million in young males. Young males infected with the virus are up 6 times more likely to develop myocarditis than those who have received the vaccine.