The chances of myocarditis didn't seem to decrease with age as fast as the chances of a serious case of the virus, so maybe there's an inflection point somewhere... Could be at three weeks before birth though for all I know.

In the UK, back in July 2021 the government's scientific advisers said, based on the evidence at the time, the health benefits of universal vaccination in children and young people below the age of 18 years do not outweigh the potential risks [1].

Subsequently better evidence became available, and it was decided to extend vaccination to under-18s.

Perhaps whatshisface is merely recalling six-month-old official advice?

[1] https://www.gov.uk/government/publications/covid-19-vaccinat...