> Children are at exceptionally low risk from Covid.

Low risk of death, yes. But still a substantial risk of long lasting severe effects: https://assets.publishing.service.gov.uk/government/uploads/...

A complete loss of sense of taste, or chronic fatigue are both entirely possible outcomes with children, and at this time, it's not clear at all how long these effects last.

Conversely, the effects of myocarditis, while unpleasant, are fairly well understood (and at least one physician I've spoken to was of the opinion that the vaccine related risk was overstated, as the base rate in that age group was bound to be higher than reported, due to the mild nature of most cases, so some of the elevated rates appear to be due to closer post-vaccination scrutiny).