The preprint observational study using U.K. health system data also found the Pfizer-BioNTech COVID-19 vaccine provided children and teens with only about 14 to 15 weeks of protection against testing positive for the virus.

https://childrenshealthdefense.org/defender/kids-teens-pfizer-covid-vaccine-myopericarditis-only-vaxed-groups/

AND

OpenSAFELY: Effectiveness of COVID-19 vaccination in children and adolescents

https://www.medrxiv.org/content/10.1101/2024.05.20.24306810v1.full.pdf