Transient recovery and renewed decline in HPV vaccination coverage in Cameroon after single-dose and gender-neutral vaccination: a secondary analysis of national immunisation coverage estimates, 2020–2025

Abstract Background Cameroon adopted a single-dose gender-neutral human papillomavirus (HPV) vaccination schedule in January 2023. Girls’ first-dose coverage rose sharply to 68% in 2023 before declining to 36% in 2024 and further to 30% in 2025, representing a net two-year decline of 38 percentage points from the 2023 peak. The central analytical question was what operational, policy, and system factors plausibly account for this trajectory. Methods We conducted a health policy analysis informed by Walt and Gilson’s health policy triangle and a root-cause-to-intervention logic model to address this question and propose an evidence-informed girls-first recovery framework. Primary data were WHO and UNICEF Estimates of National Immunization Coverage (WUENIC) 2025 revision estimates for Cameroon, including HPV first dose and completed series among girls from 2020 to 2025, and coverage for 11 comparator antigens with stable indicator definitions across the 2024 and 2025 revisions. WUENIC Estimate Descriptions and WHO/UNICEF 2025 revision notes were reviewed for documented stockout events and reporting-method context. Results Under the former two-dose schedule, dose-completion attrition was marked: estimated dropout was 76% in 2021 and 70% in 2022. An apparent 2023 supply paradox suggests a plausible role for policy, delivery, and demand-side factors: despite a four-month national and subnational stockout affecting the first and third doses of diphtheria-tetanus-pertussis-containing vaccine, HPV coverage nearly tripled that year. By 2025, all 11 comparator antigens had improved from 2024 while remaining substantially higher than HPV coverage; the HPV-specific coverage gap widened for every comparator antigen assessed. This pattern is consistent with an HPV/adolescent-specific delivery and sustainability barrier rather than general immunisation-system weakness. Conclusions The analysis suggests that renewed recovery may depend on reliable supply, protected school-based delivery, strategic communication, outreach for underserved girls, multi-year faith-sector engagement, and time-limited girls-first prioritisation until enabling conditions for gender-neutral vaccination are restored.