Potential benefits of optimised varicella vaccination scenarios in a western Chinese province: a modelling study using real-world data

BACKGROUND: Varicella remains a major public health concern in China, where the vaccine is self-paid, leading to delayed and inequitable coverage. Recent policy reforms aim to unify vaccine management and compensation, yet the public health impact of improved vaccination timeliness remains unclear. This study assessed the long-term benefits of optimising varicella vaccination timeliness and coverage in a resource-limited setting in western China, using Shaanxi province as a representative example. METHODS: A dynamic age-structured compartmental model was developed to simulate varicella transmission from 2017 to 2054, calibrated with surveillance data and real-world vaccination records from a provincial immunisation information system. Three scenarios were compared: (1) maintaining current vaccination coverage and timeliness; (2) improving timeliness only; and (3) improving both coverage and timeliness to National Immunisation Programme (NIP) levels. Primary outcomes included annual varicella incidence and cumulative varicella-related deaths over 30 years (2025-2054). Sensitivity analyses assessed the robustness of results. FINDINGS: According to immunisation system data, varicella vaccine coverage in the 2017 birth cohort was 60.8% for the first dose and 41.9% for the second, with only 14.7% and 0.7% of children receiving the first and second doses on schedule, respectively. Over a 30-year projection period, model simulations indicated that improving vaccination timeliness alone would reduce cumulative varicella cases by 67.7% and deaths by 69.1% compared with the status quo. Simultaneous improvements in coverage and timeliness further decreased cumulative cases by 89.3% and deaths by 90.8%, leading to near elimination of childhood varicella by 2031. These findings remained robust across sensitivity analyses. CONCLUSION: Optimising varicella vaccination timeliness and coverage could substantially reduce disease burden in resource-limited settings. Incorporating the vaccine into the NIP could yield the greatest benefits, while improving timeliness under a more integrated management framework may represent a feasible interim policy direction for varicella control in China and similar settings.