Impact of HPV Vaccination Against Cervical Lesions and Genital Warts in Colombia. an Ecological Assessment

The goal of this observational study is to assess the impact of HPV vaccination on cervical lesions and genital warts in Colombian birth cohorts. The study examines the trends in healthcare services usage related to these conditions, particularly among vaccinated and unvaccinated populations. The main questions it aims to answer are: Have health services usage rates for preneoplastic cervical lesions and genital warts decreased among cohorts of girls eligible for HPV vaccination after the vaccine's introduction? Have there been reductions in health services usage for genital warts among male cohorts of the same birth years as vaccinated girls? Researchers will compare health services usage trends between vaccinated and unvaccinated populations, as well as geographical areas with differing levels of HPV vaccination coverage, to evaluate the impact of the HPV vaccination program. Participants will not be directly involved, as this is a retrospective analysis of existing healthcare records from various national databases, assessing the frequency of healthcare services related to preneoplastic lesions and genital warts, as well as vaccination coverage at national, departmental, and municipal levels.

This study is an observational ecological assessment aimed at evaluating the impact of the HPV vaccination program on the incidence of cervical preneoplastic lesions and genital warts in Colombia. The analysis compares trends in health services usage across different birth cohorts of girls and boys, exposed and unexposed to the HPV vaccine, using secondary data sources such as the National Health Service Records (UPC) and individual healthcare provision records (RIPS). The study will employ a retrospective time-series analysis, assessing the frequency of healthcare encounters related to the targeted conditions (genital warts and preneoplastic lesions) by birth cohort and vaccination status. The primary objective is to determine whether there has been a significant reduction in healthcare service use for these conditions following the introduction of the HPV vaccine in 2012. Secondary objectives include evaluating geographical variations in HPV vaccine coverage at the departmental and municipal levels and their association with the trends in healthcare service usage. This will help ascertain if higher vaccine coverage corresponds to lower rates of genital warts and preneoplastic cervical lesions. The analysis will rely on both temporal (longitudinal) and geographical (cross-sectional) comparisons. Temporal trends will examine changes before and after the vaccine's introduction, while geographical analysis will compare regions based on varying vaccination coverage levels. Exposure will be categorized according to birth cohort (girls born between 1996 and 2003) and vaccination rates in different geographical areas. The data analysis will include calculating the average annual rates of healthcare service utilization for both genital warts and preneoplastic lesions, stratified by sex, age group, and region. Statistical methods such as incidence rate ratios (IRRs) and 95% confidence intervals will quantify the association between HPV vaccination and healthcare service usage. The study will also assess potential biases, including information bias due to variability in diagnosis and reporting practices across different health service providers. By utilizing existing records and implementing robust statistical approaches, the study aims to contribute valuable insights into the effectiveness of HPV vaccination in a middle-income country, where cervical cancer prevention strategies are not as comprehensive as in high-income countries. The study is anticipated to run for one year, with results presented to both scientific audiences and health policy decision-makers to support the optimization of HPV vaccination strategies in Colombia.