Human papilloma virus (HPV) is an oncovirus responsible for causing genital warts, as well as cervical, vulval, vaginal, penile, anal and oropharyngeal cancers. Whilst many HPV serotypes have been identified, HPV-6 and HPV-11 are responsible for the majority of noncancerous genital warts and HPV16 and HPV-18 are associated with 60% of HPV associated cancers (15). Australian men with HIV infection were almost twice as likely to carry the oncogenic HPV-16 serotype than were HIV negative homosexual men (44.3% vs 25.4%) (16). HIV-infected people have an increased risk of acquiring HPV infection and associated cancers, the risk of which increases in those with low CD4+ T cell counts and in MSM (16-18).
The original quadrivalent vaccine (4vHPV) developed in Australia was a virus-like particle (VLP) vaccine containing the major capsid protein (L1) of HPV types 6, 11, 16, 18. The current 9vHPV vaccine contains L1 proteins of five additional serotypes (31, 33, 45, 52 and 58), which account for an extra 10% of HPV-related malignancies. Studies of the original 4vHPV vaccine have shown it to be safe and immunogenic in HIV positive people across a wide age group (19-21). Serum levels of antibodies to HPV proteins in the vaccine are superior to those occurring from natural immunity and are higher in patients with a high CD4+ T cell count and low HIV viral load, perhaps supporting deferring vaccination until patients are established on ART (21).
Current funding for the HPV vaccine is limited to females up to 45 years and males up to 26 years. This is based on cost-effectiveness from clinical trial data in HIV negative individuals. The vaccine is administered at 0, 1 and 6 months and if interrupted the course should be completed rather than restarted.