IMPACT OF HUMAN PAPILLOMAVIRUS (HPV) VACCINATION IN CHINA: COMPARATIVE COST-EFFECTIVENESS BETWEEN AREAS OF HETEROGENEOUS RISK

Purpose:  China has a low incidence rate of cervical cancer (6.8 per 100,000) compared with other Asian countries such as India (30.7 per 100,000). However, the large population and heterogeneity of risk across regions account for a high burden of disease, nearly 10% of worldwide cases.  The availability of effective prophylactic vaccines against two of the most common cancer-causing types of HPV have the potential to avert cancer deaths, but the benefits and cost-effectiveness could differ among regions.  
   Methods: We used likelihood-based methods to calibrate a first-order Monte Carlo simulation model of the natural history of HPV and cervical cancer to epidemiologic data in a high-risk province in northern China (Shanxi) and a low-risk province in southeastern China (Guangdong).  We used good-fitting parameter sets from the two calibrated models to assess reductions in cancer risk and cost-effectiveness of HPV-16,-18 vaccination in adolescent girls. Vaccine cost, coverage, target age and immunity duration were varied in sensitivity analysis.
   Results:  Assuming lifelong type-specific immunity and 70% vaccination coverage in 9-year-old girls, the lifetime cancer risk was reduced by ~40%, though the implications for cases averted in the two regions differed greatly due to differences in the baseline risk. If vaccination does not occur until age 18, benefits are reduced by more than 50%. At a cost per-vaccinated girl of $25 (~$5 per dose plus wastage, support, and programmatic costs), cost-effectiveness ratios varied from $110 per year of life saved (YLS) in the high-risk region to $2,370/YLS in the low-risk region. At higher vaccine costs, ratios increased dramatically; for example, in the low-risk region, at $400 per-vaccinated girl, vaccination was $39,000/YLS. Assuming the vaccine provides 20 years of protection, the cost-effectiveness ratios more than double. Implications for affordability differ from considerations of cost-effectiveness, and increasingly, decision makers considering introduction of a new vaccine rely on information about both. To place the financial constraint in context, vaccinating 70% of just a single birth cohort of 9-year-old girls in China would exceed well over $100 million.
   Conclusions:  Cost-effectiveness of HPV-16,-18 vaccination in China will depend on vaccine costs and effective coverage of pre-adolescent girls. As it is more cost-effective to preferentially target high-risk regions, concerns about affordability at the national level might imply preferential targeting is preferred for an initial program.