Could one HPV shot be just as good as two? That's the question medical experts are actively debating, and the answer could reshape how millions of preteens are vaccinated against one of the leading causes of cancer in the U.S. HPV is responsible for nearly 50,000 cancer cases annually, including ~90% of cervical and anal cancers. The vaccine has been a clear success story — dramatically cutting infections, genital warts, and precancerous lesions since its debut in 2006.

The push toward a single-dose recommendation gained momentum after a Costa Rica study tracking 20,000+ girls over 5 years found one shot offered ~97% protection against cervical cancer — on par with two doses. The American Academy of Pediatrics is actively exploring a guidance update, though experts caution that data on boys and non-cervical cancers remain limited. For now, two doses are still the official recommendation.

By the Numbers:

• ~50,000 HPV-related cancer cases diagnosed in the U.S. each year
• ~90% of cervical and anal cancers are attributed to HPV
• ~97% protection against cervical cancer from a single HPV dose (Costa Rica study)
• Vaccinated males are ~50% less likely to develop HPV-related head, neck, and other cancers
• Only ~63% of U.S. teenagers have completed both recommended doses — flat for 4 years

Why it matters: A shift to a single-dose schedule could simplify vaccination, reduce barriers, and potentially boost the stubbornly flat 63% completion rate among U.S. teens — getting more kids protected against a preventable cancer.