Mathematical models of cervical cancer prevention in the Asia Pacific region.

Using population-based and epidemiologic data for 25 countries in Asia (22 GAVI-Alliance eligible countries, Thailand, China and Japan), a model-based approach was used to estimate averted cervical cancer cases and deaths, disability-adjusted life years (DALYs) and incremental cost-effectiveness ratios (I$/DALY averted) for vaccination of young adolescent girls against human papillomavirus (HPV) types 16 and 18. Absolute reduction in lifetime cancer risk varied between countries, depending on incidence, proportion attributable to HPV-16 and -18, and population age-structure; for example, with 70% coverage, cancer reduction was 57% in Indonesia, whereas in Cambodia, it was 49%. Screening of women over age 30 three times per lifetime, after vaccinating them as pre-adolescents, is expected to provide an additional 20% to 30% mortality reduction. Of the 22 GAVI-Alliance eligible countries, India, Bangladesh, Vietnam and Indonesia account for 87% of the total DALYs averted. Assuming a cost per vaccinated girl of I$10 ($2 per dose), the cost per DALY averted is less than I$250 in 18 of 22 countries. Assuming a cost per vaccinated girl of I$25, the cost per DALY averted is I$1,360 in China compared with I$250 in Thailand, reflecting the greater number of girls that need to be vaccinated to prevent a death from cervical cancer in China. Vaccine price has an even greater effect on predicted affordability. For the 22 GAVI Alliance-eligible countries, vaccinating 5 consecutive birth cohorts at 70% coverage would cost over US $500 million versus almost US $1.3 billion at per dose costs of $2 and $5, respectively. Including China and Thailand would add US $251 million to US $1.4 billion at per dose prices of $2 and $12.25, respectively. In the countries we assessed, vaccination of young adolescent girls against HPV-16 and -18 could be very cost-effective if the cost per vaccinated girl is less than I$10-I$25; for it to be affordable, however, even with financing assistance, vaccine prices may need to be even lower.