Overview

• A JAMA Pediatrics study tracked six Cincinnati cohorts of 2,335 women from 2006 to 2023 as vaccination coverage rose from 0% to 82%.
• Among vaccinated participants, infections by types targeted by the 2‑valent vaccine fell 98.4%, 4‑valent fell 94.2%, and 9‑valent fell 75.7%.
• Unvaccinated women also saw declines in earlier vaccine types, with 2‑valent infections down 71.6% and 4‑valent down 75.8%, indicating herd protection.
• Authors conclude the declines were driven by vaccination rather than behavioral changes and note that vaccinating boys likely strengthened community effects.
• Herd protection for the newer 9‑valent vaccine remains unconfirmed due to limited data, and only about 27% of girls globally have received at least one dose.