[Temporal characteristics of respiratory syncytial virus in Jiangsu Province from 2024 to 2025: a study using the annual cumulative proportion method].

Objective

To define the respiratory syncytial virus (RSV) epidemic period using the annual cumulative proportion (ACP) method, and to analyze the temporal characteristics of RSV in Jiangsu Province from 2024 to 2025.

Methods

RSV nucleic acid testing data from 17 sentinel hospitals between week 23 of 2024 and week 22 of 2025 were included. Epidemic onset and offset were defined using 10% and 90% ACP thresholds, respectively, with stratification by region, age, clinical presentation, and subtype. Positivity rates were compared using χ² tests, and between-group differences in epidemic timing were assessed using bootstrap analysis. Sensitivity analyses were also performed.

Results

A total of 19 830 respiratory specimens were included, of which 360 were RSV-positive, yielding an overall positivity rate of 1.82%. RSV positivity rates differed significantly by region, age group, and clinical surveillance category (P<0.05). The positivity rate was higher among severe acute respiratory infection (SARI) cases than among influenza-like illness (ILI) cases (2.52% vs. 1.42%; χ²=30.52, P<0.001). The ACP-defined epidemic period extended from week 50 of 2024 to week 18 of 2025. Compared with northern Jiangsu, epidemic onset in southern Jiangsu occurred 8 weeks earlier (95%CI:-18 to -3), and the epidemic duration was 7 weeks longer (95%CI: 1 to 16). Epidemic onset among SARI cases occurred 4 weeks earlier than among ILI cases (95%CI:-10 to -1).

Conclusion

RSV is prevalent during winter and spring in Jiangsu Province from 2024 to 2025. Differences in epidemic timing are observed across geographic regions and clinical surveillance categories.