Why don't schools do sti or std vaccinations?

The only vaccines available are for HPV and HIV. School vaccine requirements vary by state. Some states require HPV vaccines, but most do not. HPV is prevalent in school-aged children. HIV is not common enough too require everyone to be vaccinated. Political pressure from anti-vaccine people is the main reason some states do not require vaccines.

As far as I know there only is one vaccine and it is HPV and they do give them to high school pupils here in UK

Weed out the sexual predators and the weak. This ensures the adult population reproduces viable individuals constituting fewer genetic mutations effecting sexualy deviant behavior.