The HPV vaccine's power to prevent cervical cancer is firmly established; whether its protection extends to the rarer cancers of the vulva and vagina has been harder to demonstrate. A Karolinska Institutet register study in JAMA Oncology, Quadrivalent Human Papillomavirus Vaccine and High-Grade Vulvovaginal Lesions, addresses the question at national scale, following a cohort of 778,943 women, of whom 256,353, or 32.9 per cent, had received at least one dose of the vaccine targeting HPV types 6, 11, 16 and 18.
Vaccinated women developed high-grade vulvovaginal lesions, the precancerous changes that precede these cancers, at an incidence rate ratio of 0.63 compared with unvaccinated women, corresponding to roughly 37 per cent lower risk. The timing of vaccination mattered considerably: women vaccinated before age 17 had a 57 per cent lower rate of vaginal or vulvar precancerous lesions than unvaccinated women, reinforcing the case for immunisation well before exposure.
The authors note the study's limitations, including possible misclassification of some lesions of cervical origin as vaginal, and the absence of HPV typing data for the lesions themselves, which prevents direct attribution to vaccine-covered virus types. Even so, the study extends the vaccine's documented benefits to a further set of HPV-driven diseases, strengthening the public health rationale for achieving high vaccination coverage in early adolescence.