Earlier quoted context omitted.
Not just children under 4. There is a study going around that found 12-15 year olds are ~5X more likely to be hospitalized due to vaccine induced myocarditis than hospitalized due to covid.
source ?
https://www.tga.gov.au/periodic/covid-19-vaccine-weekly-safe...
Table 2:
Age 12-17 boys Comirnaty (Pfizer): 10.6 per 100,000 doses. 1/10000.