Preventing cervical cancer and genital warts - How much protection is enough for HPV vaccines?

HPV associated disease is a global health problem: 5.2% of all cancers are HPV associated with HPV 16 and 18 accounting for 70% of cases of cervical cancer. Genital warts caused by HPV 6 and 11 have a lifetime risk of acquisition of 10%. HPV vaccines are subunit vaccines consisting of virus like particles comprised of the L1 major capsid protein. Two vaccines have been licenced since 2006/2007 and are in the National Immunisation programmes in 62 countries. Both vaccines include HPV 16 and 18 VLPs and one also includes HPV 6 and 11. The vaccines are highly immunogenic and well tolerated. Genital HPV is a sexually transmitted infection with peak incidence occurring just after the onset of sexual activity and the routine cohort for immunisation in almost all countries are adolescent girls 9-15 years of age with or without catch up for older adolescents and young women. Population effectiveness is now being demonstrated for these vaccines in countries with high vaccine coverage. HPV vaccines are highly immunogenic and effective and the original 3 dose schedules have already been reduced, for those 14 years and under, to 2 for both licenced vaccines. There is preliminary evidence that 1 dose of vaccine is as effective as 2 or 3 in preventing persistent HPV infection in the cervix in young women and further reductions in dosage may be possible if supported by appropriate virological, immunological and modelling studies.