INCREMENTAL BENEFITS AND COST-EFFECTIVENESS OF A CATCH-UP HPV VACCINATION PROGRAM IN NORWAY

Purpose: School-based vaccination of 12-year-old girls against human papillomavirus (HPV) was introduced in Norway in 2009, free of charge. Since the vaccine is ideally targeted to young individuals prior to HPV exposure, catch-up vaccination for girls over age 12 was not publicly funded. Our objective was to estimate the cost-effectiveness of a one-year female catch-up program (starting in 2014) up to age 26.   

Method: We calibrated a previously published dynamic model of HPV transmission to fit observed HPV prevalence and cervical cancer incidence in Norway. Under various scenarios of catch-up vaccination in females, we projected reductions in HPV incidence over multiple birth cohorts, including both direct and indirect benefits, and applied these reductions to a microsimulation model of cervical cancer and incidence-based models for non-cervical HPV-related diseases. We adopted a societal perspective and assumed that vaccination of females age >19 years would incur higher delivery costs (i.e., through their family physician). Scenarios reflecting 50% coverage of women up to age 20, 22, 24 or 26 were compared to a baseline strategy assuming that these cohorts were not vaccinated. Sensitivity analyses were conducted on vaccine cost (market vs. tender price) and differential uptake among targeted women.

Result: The marginal benefit of the vaccine decreased as the upper bound of the catch-up age increased. For example, at 50% coverage, the cohort of girls aged 18-years-old in 2014 gained an absolute 21% in cumulative reduction in HPV-16 incidence, compared to no catch-up campaign, while for the cohort of girls aged 26-years-old, this gain was only 10%. Cost-effectiveness followed a similar trend. At the current market price of the vaccine, catch-up can only be extended to age 22 while still remaining below Norway’s willingness-to-pay threshold (≈$83,000/QALY), compared with vaccinating 12-year-old girls only. However, the tender price of the vaccination (not publicly available) is believed to be less than 50% of the market price, in which case a catch-up program to age 26 falls below the threshold. Results remained stable for a catch-up campaign achieving only 30% coverage.

Conclusion: At current market price, a one-year catch-up program up to age 22 is likely to be cost effective; however, at the assumed tender price, HPV vaccination may be extended to age 26 while remaining cost-effective.