HPV vaccines

The vaccines currently available provide protection vs. 6, 11, 16, 18, 31, 33, 45, 52, and 58 (type 6 and 11 are responsible for most anogenital warts). ^{Go to footnote 11}
Both Bivalent and Quadrivalent Vaccines show cross-protection, with the bivalent vaccine (targeting HPV-16/18) generally provides stronger and more consistent cross-protection, particularly against HPV-31, HPV-33, and HPV-45. Some studies also report partial protection against HPV-35, HPV-52, and HPV-58, though the evidence is less robust and more variable. ^{Go to footnote 22}

Meta-analysis: Three doses of the bivalent (Cervarix) and quadri-valent (Gardasil) vaccines offered significant protection against cervical adenocarcinoma in situ associated with HPV16 and HPV18 among young women (aged 15–26 years): 88% (95%CI 30–98%). Trials among vaccine recipients not already infected with HPV showed high efficacy against high-grade cervical, vulvar and vaginal lesions: 98% (95%CI 93–100) for CIN2+ and 100% (95%CI 83–100) for vulvar and vaginal intraepithelial neoplasia grade 2+ caused by the HPV types in the quadrivalent vaccine. Approval of the 2-dose schedule was based on demonstration of non-inferiority of the immune response when compared with young adult women (16-26 years of age) in whom 3-dose efficacy has been proven (immunobridging). A one-dose schedule is supported by WHO given that post-hoc analyses of efficacy trials, and post-licensure observational studies among African females (15-20 years of age) have demonstrated that a single dose of HPV vaccine is sufficient to elicit an immune response that provides similar protection as a multidose regimen against initial and persistent HPV infection.

With a multidose schedule, antibody titres remain high for up to 12 years for the bivalent (Cervarix) vaccine for girls vaccinated at age 16-17, up to 15 years for quadrivalent (Gardasil) vaccine, and for at least 6 years for the more recently licensed nonavalent vaccine (Gardasil-9). ^{Go to footnote 33, Go to footnote 44, Go to footnote 55}  GMT following a single dose remain stable through at least 10-16 years.  ^{Go to footnote 66, Go to footnote 77}