Impact of human papillomavirus vaccine against anal human papillomavirus infection, anal intraepithelial neoplasia, and recurrence of anal intraepithelial neoplasia: a systematic review and meta-analysis.

There is strong evidence for high VE against anal HPV infection and AIN in HIV-negative individuals vaccinated aged ≤26 years. Lower impact in ITT than PPE populations, and lack of significant effect in PLWH >26 years, however, highlights greatest vaccine impact in populations more naïve to sexual exposure to anal HPV.