The predicted impact of vaccination on human papillomavirus infections in Australia

Vaccines based on human papillomavirus (HPV) 16 and 18 virus-like particles have the potential to prevent approximately 70% of cervical cancers. In Australia, public vaccination against HPV commenced in April 2007, and includes routine vaccination of females aged 12-13 years, and a 2-year school and GP-based catch-up in females aged 12-26 years. The objectives of this study were to estimate initial vaccination coverage rates, to describe current patterns of sexual behavior in young females, and to predict the impact of vaccination on HPV16 infections. We reviewed early coverage data, estimating that coverage in 2007/2008 will reach 86% (feasible range 67-90%) for 12- to 13-year-old girls, with lower rates attained in older females. A review of survey data found that the median age of first intercourse in Australian females is 16 years, with approximately 90% of women sexually active at 22 years. Using these data, we performed an analysis of HPV transmission to predict the impact of vaccination on HPV infection rates. The public program is predicted to result in a reduction in the age-standardized incidence of HPV16 infections of 56% by 2010 (feasible range 48-61%), and 92% by 2050 (feasible range 76-95%). Elective vaccination of older women and vaccination of males may provide some incremental gains, but the benefits to women of vaccinating males will be less if coverage of females remains high. In conclusion, the current vaccination program is expected to result in a substantial and rapid reduction in the incidence of HPV16 in Australia.