Since 2012, vaccinating against human papillomavirus (HPV) in preadolescent girls in schools has been a part of the national vaccination programme for children in Sweden. HPV vaccination coverage among girls has since been around 80%. The main goal with the introduction of the vaccine was to protect girls from infection with high-risk types of HPV that may cause cervical cancer. The vaccine also prevent other cancer types of which some are prevalent among men, such as oropharyngeal, anal, and penile cancer. The aim of this study was to assess the cost-effectiveness of including HPV-vaccination for preadolescent boys in the Swedish national immunization program by comparing health effects and costs of all HPV-related disease in a situation with a gender neutral vaccination programme compared to only vaccinating girls.
We used a dynamic compartmental model to simulate the transmission of HPV 16/18 in the population, accounting for indirect effects of vaccination through herd immunity. The model accounted for sexual behaviour, such as age preferences of sexual contacts and men who have sex with men. The main outcome was number of individuals with all HPV-related cancers as well as CIN. The data in the model were based on epidemiological studies, demographic statistics, cancer registers and other Swedish population-based healthcare and sociodemographic registers that capture all healthcare interactions. Estimates were calibrated to fit Swedish empirical data.
Costs included in the analysis were those incurred when treating HPV-related cancer and CIN, production losses during sick-leave, and acquisition and administration of the vaccine. Health effects were measured as quality-adjusted life years (QALY). The time horizon was set at hundred years, and both effects and costs were discounted with 3% annually. All health effects and costs were accumulated over the time horizon and used to create the incremental cost-effectiveness ratio (ICER). Several variables, such as price of the vaccine, vaccination coverage, vaccine effectiveness, and herd immunity were varied in sensitivity analyses to illustrate their impact on the results from the cost-effectiveness analysis.
Preliminary results indicate that a gender neutral vaccination programme will reduce HPV-related cancer and CIN during the model’s time horizon, both due to direct effects of the vaccine as well as indirect effects decreasing HPV prevalence in the population. The potential cost-effectiveness of a gender neutral programme is dependent on the price of the vaccine, the lower the price the more favourable it is to vaccinate boys from a societal perspective.