There are resources on how to get vaccinated without your parents agreeing here: https://vaxopedia.org/2018/09/25/how-can-i-get-vaccinated-if-my-parents-are-anti-vaccine/
Unfortunately the law varies state by state (not to mention country by country) so there’s not One Weird Trick :/
@andrhia
in England and Wales anyone over 16 who has mental capacity (understands the basics of what the treatment is) consent to it and even younger children can do so without parental approval in emergency situations.. (Scotland and NI have slightly different laws although its likely vaccinations are available everywhere, the health authorities here encourage it)
https://www.nhs.uk/conditions/consent-to-treatment/children/