Abstract:

ObjectiveTo analyze the epidemiological characteristics of human respiratory syncytial virus (HRSV) infection among acute respiratory infection (ARI) cases in Sichuan Province for scientific evidence for prevention and control of HRSV in local area. Methods ARI cases monitored at 7 sentinel hospitals for multi-pathogen surveillance of ARI in Sichuan Province between 2024 and 2025 were selected as the study subjects. Descriptive epidemiological methods were applied to analyze the demographic, temporal and regional distribution characteristics of HRSV-positive cases, as well as the distribution of HRSV subtypes. Results The overall positive rate of HRSV among the monitored subjects was 3.65% (803/22 003), in which the positive rate was 3.11% (456/14 680) for outpatients and emergency influenza-like illness (ILI) cases, and 4.74% (347/7 323) among hospitalized severe acute respiratory infection (SARI) cases, with statistically significant difference (χ²=37.02, P<0.001). The HRSV positive rate was 3.89% (445/11 443) in males and 3.39% (358/10 560) in females, showing a statistically significant difference (χ²=3.88, P<0.05). Overall, the HRSV positive rate decreased significantly with increasing age (χ²_trend=428.09, P<0.001, Z=-20.69), with children aged 0-5 years being the dominant affected group (81.57%, 655/803). Temporally, higher positive rates were observed from October to March of the following year, and the lower rates were seen from May to July. Geographically, Dazhou and Chengdu exhibited relatively higher positive rates (8.29% and 5.43%, respectively). The difference in positive rate was statistically significant among surveillance regions (χ²=390.52, P<0.001). A total of 73 samples from 2025 were subjected to HRSV subtype testing, which revealed HRSV subtype A in 60 cases (82.19%), subtype B in 12 (16.44%), and A/B co-infection in 1 (1.37%). Conclusion HRSV infection in Sichuan Province from 2024 to 2025 predominantly occurs in children aged 5 years and younger, and the infection rate gradually declines with increasing age. The epidemic peaks from late autumn to the following spring, with substantial regional differences in positivity rates. Subsequent prevention and control efforts should focus on younger children, while expanding coverage of viral subtype surveillance and continuously estimating the epidemic trends.

Key words: Human respiratory syncytial virus, Acute respiratory infection, Sichuan Province