Modeling the health and economic implications of adopting a 1-dose 9-valent human papillomavirus vaccination program in adolescents in low/middle-income countries: An analysis of Indonesia

Abstract

Background: Recent evidence suggests that 1 dose of the human papillomavirus (HPV) vaccine may have similar effectiveness in reducing HPV infection risk compared to 2 or 3 doses.

Objective: To evaluate the public health impact and cost-effectiveness of implementing a 1-dose or a 2-dose program of the 9-valent HPV vaccine in a low- and middle-income country (LMIC).

Methods: We adapted a dynamic transmission model to the Indonesia setting, and conducted a probabilistic sensitivity analysis using distributions reflecting the uncertainty in levels and durability of protection of a 1-dose that were estimated under a Bayesian framework incorporating 3-year vaccine efficacy data from the KEN SHE trial (base-case) and 10 year effectiveness data from the India IARC study (alternative analysis). Scenarios included different coverage levels targeted at girls-only, or girls and boys. Costs and benefits were computed over 100 years from a national single-payer perspective.

Results: Depending on the coverage and target population, the median number of cancer cases avoided in 2-dose programs ranged between 600,000-2,100,000, compared to 200,000-600,000 in 1-dose programs. The 1-dose programs are unlikely to be cost-effective compared to 2-dose programs even at low willingness-to-pay (WTP) thresholds. The girls-only 2-dose program tends to be cost-effective at lower WTP thresholds, particularly in scenarios with high coverage, dose price and discount rate, while the girls and boys 2-dose program is cost-effective at higher WTP thresholds. In the alternative analysis, 1-dose programs have higher probability of being cost-effective compared to the base-case, particularly for low WTP thresholds (less than 0.5 GDP) and for high coverage, dose price and discount rate.

Conclusion: Adoption of 1-dose programs with 9-valent vaccine in an LMIC resulted in more vaccine-preventable HPV-related cancer cases than 2-dose programs. The 2-dose programs were more likely to be cost-effective than 1-dose programs for a wide range of WTP thresholds and scenarios.

Fig 1

Estimated cancer cases avoided by coverage scenario for the four different vaccination strategies compared to no vaccination, over a 100-year horizon for the base-case (A) and alternative (B) distributions. The figure shows all cancers combined and the portions due to cervical and non-cervical cancers. The boxes in the boxplots cover the 25% to 75% quartiles, the white vertical lines represent the median and whiskers represent the minimum and maximum values.

Fig 2

Estimated non-cervical cancer cases avoided compared to no vaccination by coverage scenario for the four different vaccination strategies, over a 100-year horizon for the base-case (A) and alternative (B) distributions. The figure shows all non-cervical cancers combined and the portions due to female and male cancers. The boxes in the boxplots cover the 25% to 75% quartiles, the white vertical lines represent the median and whiskers represent the minimum and maximum values.

Fig 3

Cost-effectiveness acceptability curves by coverage scenario, for each of the four different vaccination strategies, assuming $20 USD per dose, for the (A) base-case and (B) alternative distributions. The vertical dashed lines represent the WTP thresholds for 0.5, 1 and 2 times GDP per QALY, respectively.