Evolving trends in HPV vaccination coverage among women aged 9-45 in Chengdu, China: insights from 2017 to 2023.

Background: Chengdu, China, is facing an increasing burden of cervical cancer. Although human papillomavirus (HPV) vaccines have been introduced in China since 2016, vaccination coverage remains suboptimal, and data on regional disparities are limited. In 2021, Chengdu implemented a subsidized HPV vaccination program targeting girls aged 13-14 years. This study aims to evaluate HPV vaccination coverage among females aged 9-45 years in Chengdu from 2017 to 2023, stratified by age group, geographic area, and vaccine type, and to examine changes in vaccination coverage among girls aged 13-14 years following the city's enrollment in the pilot subsidy program.

Methods: HPV vaccination data were sourced from the Sichuan Provincial Immunization Information System. Descriptive analyses assessed annual and cumulative vaccination coverage from 2017 to 2023 among females aged 9-45 years in Chengdu. An interrupted time series (ITS) analysis using a segmented regression model (SRM) was conducted to quantify changes in vaccination rates following program implementation among girls aged 13-14 years.

Results: From 2017 to 2023, first- and full-dose HPV vaccination coverage among females aged 9-45 years in Chengdu showed significant upward trends across age groups, geographic areas, and vaccine types. By 2023, cumulative first-dose coverage reached 34.17 %, with full-dose coverage at 24.40 %. Notably, vaccination rates for girls aged 13-14 years exhibited markedly higher first- and full-dose coverage compared to pre-program levels (β = 1.899, p-value = 0.002; β = 4.859, p-value <0.001, respectively).

Conclusions: Following the HPV vaccination program in Chengdu, the vaccination rate for girls aged 13-14 years significantly increased. However, the overall vaccination rate for women aged 9-45 years remains relatively low, particularly among certain subpopulations. To enhance overall vaccination rates, strategic priorities should include targeted interventions for subpopulations with suboptimal coverage, expansion of pilot programs, and stronger political commitment to integrating the HPV vaccine into the National Immunization Program.