Hidalgo–Tenorio C, et al. – Researchers here determined safety and immunogenicity of the quadrivalent human papillomavirus (qHPV) vaccine in HIV–positive Spanish MSM. They also determined the prevalence of High Squamous Intraepithelial Lesions (HSIL) and genotypes of high–risk human papillomavirus (HR–HPV), as well as risk factors associated with the presence of HR–HPV in anal mucosa. Results indicated significantly higher anti–HR–HPV antibody titres in vaccinated individuals in comparison to unvaccinated controls. No serious adverse events attributable to the vaccine were evident. In the study population, 1 of every 7 patients had HSIL and the prevalence of combined infection by genotypes 16 and 18 was low. This suggests a beneficial effect of receiving qHPV vaccine. They identified older age as the main protective factor against HR–HPV infection, and non–suppressed HIV viremia as a risk factor.