Introduction: The introduction of HPV vaccination through National Vaccination Programs is expanding globally, and cervical cancer elimination is increasingly becoming a realistic scenario in many countries across the world. Ensuring that HPV vaccination programs have a population-level impact is critical to cervical cancer (CC) elimination. Accordingly, the World Health Organization (WHO) has identified monitoring HPV prevalence within populations as a proxy for the impact of vaccination as a critical element of its framework for evaluating the global strategy to eliminate CC. To this aim The IARC Public Health Decision Science Team (PHDS) has established a Center of Excellence (CHRONOS) to monitor the impact of human papillomavirus (HPV) vaccination in low- and middle-income countries (LMICs).
Objective: The CHRONOS project aims to: (1) validate and establish standardized procedures for cross-sectional surveys; (2) develop effective mechanisms for transferring knowledge to countries joining the CHRONOS network; (3) evaluate the effectiveness and robustness of the training materials; and (4) facilitate programme expansion and promote global access.
Methods: The PHDS team at IARC, building on extensive experience in HPV surveillance, has assembled a set of standardized tools that cover all stages of survey implementation, from planning to data analysis. These tools define best practices for the design and conduct of HPV prevalence surveys in low- and middle-income countries. To support the transfer and local adoption of these best practices, a structured capacity-building programme, including a dedicated curriculum and training, has been established and is currently being field-tested to evaluate its effectiveness. A mixed-methods knowledge assessment and implementation science framework has been designed to guide this evaluation. The CHRONOS initiative is currently conducted in collaboration with local partners in Bangladesh, Indonesia, Eswatini, Cambodia, and China., IARC provides online training and mentorship of local coordination teams to implement local cross-sectional surveys targeting unvaccinated birth cohorts using harmonised sampling strategies and validated HPV testing platforms to establish baseline HPV prevalence.
Results: Chronos initiated the pilot phase of its procedures and training programme in April 2025; the standardized procedures and tool had been proven effective in guiding participants adapting Study design and protocol to their settings. The fieldwork evaluation is scheduled for 2026/27 period. The implementation processes will be closely monitored to generate feedback, which is intended to refine CHRONOS methodologies. These baseline estimates will serve as a reference point for assessing future changes in HPV prevalence attributable to HPV vaccination. Moreover, the data generated in CHRONOS will play a pivotal role in informing public health decision-making at IARC, as evidenced by the METHIS initiative. This initiative has been meticulously devised to address the pressing issue of cervical cancer in low- and middle-income countries, with a specific focus on its elimination.
Conclusions: The training program, standardized procedures, data collection tools, and expertise developed within the CHRONOS pilot will serve to refine and further consolidate a standardized framework to support public health authorities in LMICs in monitoring the impact of HPV vaccination and in designing policies to accelerate cervical cancer elimination through sustainable actions.