High Effectiveness of the Changchun Baike Varicella Vaccine in a Real-World Outbreak Setting: An Observational Study from Yanji City, China

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.