[Analysis on the epidemic and genetic characteristics of varicella in Fengtai District, Beijing City, 2024-2025].

This study analyzed the epidemiological characteristics and strain genotypic distribution of varicella in Fengtai District, Beijing, utilizing population-based surveillance data from March 2024 to February 2025 combined with laboratory nucleic acid detection and genotyping.We reported 522 varicella cases with male predominance (282 cases, 54.41%) and a majority aged >15 years (358 cases, 68.58%).A bimodal incidence pattern peaked in May and November, while 161 breakthrough infections (30.8%) occurred predominantly among students aged 6-20 years.The multivariate logistic regression model analysis showed that, compared to the 0-5 years age group, individuals aged 6-14 years (OR: 2.729, 95%CI: 1.083-6.88), 15-20 years (OR: 2.495, 95%CI: 1.158-5.378), and>20 years (OR: 5.382, 95%CI: 2.478-11.689) exhibited progressively higher odds of oderate-to-severe rash; females demonstrated a lower risk compared to males (OR: 0.485, 95%CI: 0.286-0.822); regarding vaccination status, recipients of one vaccine dose (OR: 0.301, 95%CI: 0.161-0.564) and two doses (OR: 0.203, 95%CI: 0.086-0.48) showed significantly reduced risks relative to unvaccinated individuals. Genotyping of 174 specimens identified 161 VZV-positive samples, with successful ORF22/38/62 sequencing in 142 samples confirming Clade 2 predominance (141 strains, 99.3%) and one Clade 5 strain; local isolates exhibited high vaccine-strain homology (ORF22 nucleotide:99.5%-100%, amino acid:99.3%-100%) with mutation sites partially overlapping other Chinese regions.