This article broke down the figures for reported pericarditis and myocarditis following Covid jabs in 12-17yr olds between September 13, 2021 and October 23, 2021 showing the following:

In the three days between October 24, 2021 and October 26, 2021 there were 75 total reports of pericarditis and myocarditis with 16 of these without an age recorded.

In the 12-17yr age group the breakdown is:

This brings the total reported pericarditis and myocarditis events in 12-17yr olds to 121 in the period 13 September to 26 October: 44 days. An average of 2.75 a day. This excludes those where the age has not been reported.

Without context of how many teenagers in these age groups are receiving vaccines it is difficult to extrapolate the number of excess cardiac events due to the vaccines. We do know that adverse events are generally under reported. We also know that worldwide there has been an acknowledgement of pericarditis and myocarditis being known adverse events.