Safe and effective human papillomavirus (HPV) vaccines have been available since 2006, yet national vaccine introduction in many low- and middle-income countries (LMICs) progressed slowly. The authors set out to quantify how global policy events shaped the rate of national HPV vaccine introductions from 2006 through 2025. They highlighted three broad influences: evolving World Health Organization (WHO) recommendations on dosing, funding policies from Gavi, the Vaccine Alliance, and the disruptions associated with the Coronavirus Disease 2019 pandemic. Prior work has described these factors qualitatively; this study aimed to estimate their relative contributions using quantitative methods.
The analysis combined two complementary quantitative approaches. First, the authors used generalized linear models (GLMs) to test associations between predetermined policy events and the national introduction rate of HPV vaccines in LMICs. The GLMs explored different model specifications and outcome variables to assess robustness across analytic choices.
Second, the authors applied changepoint analysis to the time series of national introductions to identify years in which the trend in adoption shifted significantly. Changepoint detection provides an independent check on whether temporal inflection points align with specific policy events identified in the GLM framework.
The study compared model projections that included versus excluded selected policy events in order to estimate the incremental number of national introductions attributable to those events.
The policy determinants examined included WHO immunization schedule recommendations, notably the 2022 WHO recommendation supporting a one-dose HPV vaccine schedule, as well as expansions in Gavi funding policy for HPV vaccines during a policy window defined by the authors (2017–2025). The analysis also considered the potential disruptive effect of the COVID-19 pandemic on national introduction timelines, although relative contributions of all candidate events were assessed within the GLM framework.
Across a range of GLM specifications and alternative outcome definitions, the WHO one-dose recommendation issued in 2022 showed the strongest association with an increase in country-level HPV vaccine introductions. Some GLM variants also identified the expansion of Gavi's funding policy for HPV vaccines (2017–2025) as an important predictor of introductions, although the magnitude and statistical support for this effect varied by model.
When the authors compared model projections with and without inclusion of the WHO one-dose recommendation, the difference corresponded to an estimated 22.46 additional national HPV vaccine introductions in LMICs attributable to that recommendation. This counterfactual comparison quantified the incremental impact associated with the policy change in the study period.
Changepoint analysis of the national-introduction time series independently identified a significant increase in the rate of introductions in 2022. This temporal inflection aligns with the GLM finding that the WHO one-dose recommendation was strongly associated with increased adoption, providing convergent evidence from two analytic approaches.
The combined analytic results suggest that the WHO's 2022 guidance endorsing a one-dose HPV vaccine schedule was a primary global driver of national introduction activity in LMICs between 2006 and 2025. Expansion of Gavi funding policy also contributed in some model specifications, reinforcing the importance of financing mechanisms for national rollout.
These findings quantify policy levers that can accelerate uptake and offer actionable insights for stakeholders seeking to expand equitable access to HPV vaccination. In particular, recommendations that simplify schedules and align with financing support appear influential in prompting national introductions.
The article reports the analytic approach (GLMs and changepoint analysis) and the principal quantitative findings summarized above. Specific model parameter values, full model diagnostics, country-level data inputs, and sensitivity analyses beyond the summarized robustness checks are not reproduced here; those details were reported in the original publication. The study period covers national introductions recorded from 2006 through 2025.
This analysis appears as: Suh J et al., "Global policy determinants of national human papillomavirus vaccine introductions in 2006–2025," Expert Review of Vaccines, 2026 (Dec; volume 25, issue 1), with electronic publication on 22 September 2026. PubMed identifier (PMID) is 42770688 and the DOI is 10.1080/14760584.2026.2736328. Author affiliations include New York University, Université Laval / CHU de Québec, Harvard T.H. Chan School of Public Health, University of Oslo, Saw Swee Hock School of Public Health (National University of Singapore), London School of Hygiene & Tropical Medicine, and the University of Hong Kong.
Human papillomavirus; changepoint analysis; generalized linear model; low- and middle-income countries; vaccine
Using complementary statistical methods, the study quantifies the dominant global policy drivers of national HPV vaccine introductions in LMICs from 2006 to 2025, concluding that the WHO one-dose recommendation in 2022—and to a lesser extent expanded Gavi funding policy—were associated with measurable increases in national adoption, informing strategies to accelerate equitable vaccine access.