Objectives: This study aimed to investigate the protective effect of the Changchun Baike varicella vaccine in Yanji City from 2018 to 2024. Methods: Varicella surveillance data from 2018 to 2024 and vaccination records from 2018 to 2020 were collected from the China Disease Prevention and Control Information System and analyzed. Results: In total, 2452 varicella cases were reported in Yanji from 2018 to 2024, with an average annual incidence rate of 62.71 per 100,000 population. Notably, the annual incidence rate decreased from 142.37 per 100,000 in 2018 to 55.25 per 100,000 population in 2024. Additionally, the highest and lowest incidence rates were observed in the 10–14 and ≥40 years age groups, respectively. Moreover, the vaccine demonstrated high protective effectiveness of 98.0–99.0% for one dose and 99.0% for two doses across the study period. These estimates were derived from propensity score-matched cohorts ranging from 686 to 6990 individuals (343 to 3495 matched pairs) across three overlapping observation periods (2018–2022, 2019–2023, and 2020–2024). Conclusions: The two-dose varicella vaccination schedule demonstrated superior protective efficacy compared with the single-dose schedule.

Background: Varicella burden is closely linked to national socioeconomic development, yet systematic analyses of its non-linear relationship with the Socio-demographic Index (SDI) are lacking. This study aims to elucidate this relationship and inform equitable, context-specific strategies. Methods: Based on data from the Global Burden of Diseases 2021 study, we analyzed global trends (1990–2021) in the incidence, prevalence, mortality, and disability-adjusted life-years (DALYs) of varicella. Joinpoint regression was used to identify trend transition points, and an autoregressive integrated moving average (ARIMA) model was applied to forecast the disease burden through 2035. Analyses were conducted, and countries and territories were stratified into five SDI groups: high (SDI > 0.81), high–middle (0.70–0.81), middle (0.61–0.69), low–middle (0.46–0.60), and low (SDI < 0.46). These approaches aimed to systematically elucidate the socioeconomic gradient of the varicella burden and to specifically investigate its potential non-linear relationship with SDI. Results: From 1990 to 2021, global age-standardized mortality and DALYs declined by −45.71% (95% UI: −48.32% to −42.95%) and −36.15% (95% UI: −39.04% to −33.01%), respectively, while incidence and prevalence rates slightly increased. A significant U-shaped relationship emerged between burden and SDI, with rates highest in low- and high-SDI regions. The rise in high-SDI regions was driven by increasing incidence and prevalence from 1996 to 2015. Projections to 2035 indicate continued global decline but persistent disparities. Conclusions: The varicella burden follows a U-shaped socioeconomic gradient. Rising incidence in high-SDI regions highlights that economic development and routine pediatric vaccination alone are insufficient. Precision strategies tailored to SDI levels—closing adult immunity gaps in high-SDI, sustaining gains in middle-SDI, and expanding vaccine access in low-SDI regions—are essential.

This study aimed to investigate the protective effect of Changchun Baike varicella vaccine in Yanji City from 2018 to 2024. Varicella surveillance data from 2018 to 2024 and vaccination records from 2018 to 2020 were collected from the China Disease Prevention and Control Information System and analyzed. In total, 2,452 varicella cases were reported in Yanji from 2018 to 2024, with an average annual incidence rate of 62.71 per 100,000 population. Notably, the annual incidence rates decreased from 142.37 per 100,000 in 2018 to 55.25 per 100,000 population in 2024. Additionally, the highest and lowest incidence rates were observed in the 10–14 and ≥ 40 years age groups, respectively. Moreover, Changchun Baike varicella vaccine showed protective efficacies of 98.0–99.0% and 99% for the first and second doses, respectively, from 2018 to 2024. Importantly, the two-dose varicella vaccination schedule demonstrated superior protective efficacy compared with the single-dose schedule.