Mine was supposed to be boosted then got COVID a few days before. Mild case but really messed with school and an important extracurricular activity. So wish he could have been boosted and possibly avoided it. He will still get the booster and hopefully have super-immunity.
Also the myocarditis risk is lower with boosters than with 2nd shot, per Israeli data (slide 30 of this cdc deck):
https://www.cdc.gov/vaccines/acip/meetings/downloads/slides-2021-11-19/06-COVID-Oliver-508.pdf