MONDAY, Dec. 8, 2025 (HealthDay News) -- One dose of bivalent or nonavalent human papillomavirus (HPV) vaccine is noninferior to two doses for protecting against HPV16 and HPV18 infection, according to a study published online Dec. 3 in the New England Journal of Medicine.Aimée R. Kreimer, Ph.D., from the National Cancer Institute in Bethesda, Maryland, and colleagues examined whether one dose of an HPV vaccine was noninferior to two doses. Girls aged 12 to 16 years were randomly assigned to receive one or two doses of a bivalent HPV vaccine or one or two doses of a nonavalent HPV vaccine; 20,330 participants were enrolled and underwent randomization (1:1:1:1 ratio).The researchers found that one vaccine dose was noninferior to two doses for preventing HPV16 or HPV18 infection. The rate difference was −0.13 infections per 100 participants between one and two doses of the bivalent vaccine and 0.21 infections per 100 participants between one and two doses of the nonavalent vaccine (both P < 0.001 for noninferiority). In each of the four trial groups, the vaccine effectiveness was at least 97 percent. There were no safety concerns identified."The evidence from this trial supports the WHO alternative recommendation for single-dose HPV vaccination to achieve higher coverage while maintaining sufficiently high efficacy," the authors write.Two authors disclosed ties to the pharmaceutical industry.Abstract/Full Text (subscription or payment may be required)Editorial (subscription or payment may be required).Sign up for our weekly HealthDay newsletter