Recipients of a quadrivalent vaccine against human papillomavirus (HPV) show sustained protection against low-grade lesions associated with viral types included in the vaccine, according to a BMJ study.

The trial, conducted by the vaccine’s manufacturer, examined outcomes in some 18,000 young women who were randomized to vaccine or placebo. After a mean of 42 months, the vaccine was over 95% effective in preventing condyloma as well as low-grade cervical, vulvar, and vaginal intraepithelial neoplasia related to viral types included in the vaccine (6, 11, 16, and 18).

Its efficacy in preventing any lesion regardless of HPV type was lower — for example, only 30% against low-grade cervical intraepithelial neoplasia.