What does the HPV vaccine do?
The HPV vaccine protects against the human papillomavirus strains most associated with cancer and genital warts. The currently used vaccine in the US (Gardasil 9) covers nine HPV types — including high-risk strains 16 and 18, which together cause around 70% of cervical cancers, and strains 6 and 11, which cause 90% of genital warts. The vaccine is most effective when given before any exposure to HPV, which is why ACIP recommends routine vaccination starting at ages 11–12 (and as early as age 9).
Can adults get the HPV vaccine?
Yes. In the US, catch-up HPV vaccination is recommended through age 26 for those not adequately vaccinated earlier. For adults ages 27–45, vaccination may still help after shared clinical decision-making with a healthcare provider. The vaccine is less effective the more HPV types a person has already been exposed to, but evidence suggests it still provides meaningful protection against strains not yet acquired.
Is it worth vaccinating if you are already sexually active?
Yes, for most people. While the vaccine cannot clear existing infections, it protects against strains you have not yet been exposed to. Most sexually active adults will not have been infected with all nine strains covered by Gardasil 9. Studies in adults have shown the vaccine reduces rates of new HPV infection and associated conditions. Your PCP or a health department STD clinician can provide personalized advice based on your situation.
What about Pap tests and HPV co-testing?
Pap tests (Pap smears) and HPV vaccination work together — they are complementary, not alternatives. USPSTF-aligned screening for people with a cervix typically covers ages 21–65, with Pap alone, high-risk HPV testing, or Pap/HPV co-testing depending on age. Even vaccinated people should continue recommended cervical screening, as the vaccine does not cover all high-risk HPV strains.