Cost-effectiveness and equity impacts of three HPV vaccination programmes for school-aged girls in New Zealand

Background: As with many high-income countries, vaccination coverage against human papilloma virus (HPV) infection is not high in New Zealand (NZ) at 47% in school-aged girls for three doses. We estimate the health gains, net-cost and cost-effectiveness of the currently implemented HPV national vaccination programme of vaccination dispersed across schools and primary care, and two alternatives: school-based only (assumed coverage as per Australia: 73%), and mandatory school-based vaccination but with opt-out permitted (coverage 93%). We also generate estimates by social group (sex, ethnic and deprivation group).

Methods: A Markov macro-simulation model was developed for 12-year-old girls and boys in 2011, with future health states of: cervical cancer, pre-cancer (CIN I-III), genital warts, and three other HPV-related cancers (oropharyngeal, anal, vulvar cancer). In each state health sector costs, including additional health sector costs from extra life, and quality-adjusted life years (QALYs) were accumulated.

Results: The current HPV vaccination programme has an estimated cost-effectiveness of NZ$18,800/QALY gained (about US$9700/QALY gained using the OECD's purchasing power parities; 95% UI: US$6900 to $33,700) compared to the status quo in NZ prior to 2008 (no vaccination, screening alone). The incremental cost-effectiveness ratio (ICER) of an intensive school-based only programme of girls, compared to the current situation, was US$33,000/QALY gained. Mandatory vaccination appeared least cost-effective (ICER compared to school-based of US$117,000/QALY gained, but with wide 95% uncertainty limits from $56,000 to $220,000). All interventions generated more QALYs per 12-year-old for Māori (indigenous population) and people living in deprived areas (range 5-25% greater QALYs gained).

Interpretation: A more intensive school-only vaccination programme seems warranted. Reductions in vaccine price will greatly improve cost-effectiveness of all options, possibly making a law for mandatory vaccination optimal from a health sector perspective. All interventions could reduce ethnic and socioeconomic disparities in HPV-related disease.