A large, long-term study led by a researcher at the Albert Einstein College of Medicine and published in JAMA Pediatrics has found that thehuman papillomavirus(HPV) vaccine is highly effective at preventingHPV infectionsin real-world settings. The study also revealed significant herd immunity effects, offering protection even to young women who were not vaccinated. HPV is the most common sexually transmitted infection globally and is responsible for more than 690,000 new cancer cases annually. It is the primary cause ofcervical cancer, along with several other genital and head and neck cancers in both women and men. To assess real-world performance, the researchers conducted six separate studies in Cincinnati between 2006 and 2023, enrolling 2,335 adolescent and young adult women aged 13 to 26. Many participants were considered high-risk for HPV, with 79% reporting two or more male sexual partners and over half having a history of at least one sexually transmitted infection. Participants were categorized as vaccinated if they had received at least one dose of any of the available HPV vaccines: 2-valent, 4-valent, or the newer 9-valent vaccine. Over 17 years, vaccination rates rose from 0% to 82%, and HPV infection rates dropped substantially. Infections from HPV types targeted by the 2-valent vaccine fell by 98.4%, by 94.2% for the 4-valent, and by 75.7% for the 9-valent. Even among unvaccinated women, infection rates fell significantly, offering strong evidence of herd protection. “There are two encouraging takeaways from our study,” said lead author Dr. Jessica Kahn. “First, HPV vaccines work remarkably well in a real-world setting, even among women at high risk for HPV and who may not have received all vaccine doses. Second, we saw clear evidence of herd immunity, meaning when enough people are vaccinated, the vaccine indirectly protects unvaccinated people by reducing overall virus transmission.” Reference: DeSieghardt A, Ding L, Ermel A, et al. Population-Level Effectiveness and Herd Protection 17 Years After HPV Vaccine Introduction. JAMA Pediatr. Published online September 29, 2025. doi:10.1001/jamapediatrics.2025.3568