Qiuyao Duan, Xinwen Jin, Xiaofei Fu, An Zhu, Chaorong Ni, Jianbo Jiang, Yang Yang, Peili Jin, Hangjie Zhang, Ren Chen, Jiafeng Chen, Zhengmei Xia, Jinren Pan, Xiaowei Li, Haifang Wang, Ziping Miao, Xiaojun Lv, Zhao Yu, Xiaozhi Xu, Shunwen Qin, Yin Chen, You Li, Shelan Liu
Children aged 0-5 years were the main inferred household introducers and were highly susceptible, with infants aged <1 year the most susceptible. Household transmission frequently involved spread from children aged 0-5 years to adults, supporting age-targeted household prevention.
OBJECTIVES: To estimate the secondary HRSV infection proportion, age-specific susceptibility, inferred spread, and HRSV-A/B transmission patterns in Chinese households.
METHODS: This prospective case-ascertained household cohort in Zhejiang, China (November 2024-December 2025) recruited medically attended, laboratory-confirmed paediatric HRSV index cases aged 0-14 years. Ten-day exposure histories, Day 3/10 contact sampling, and regression models assessed household- and contact-level risk factors.
RESULTS: Among 179 households with 542 contacts, secondary infection was detected in 110 households (61.5%) and 218 contacts (40.2%); 46.3% were symptomatic. Children aged 0-5 years accounted for 86.6% (155/179) of inferred primary cases. Contact infection was highest among children aged 0-5 years (86.4% [38/44]), including all infants aged <1 year (17/17). HRSV-B-only households had higher contact-level infection odds than HRSV-A-only households (aOR 1.96, 95% CI 1.05-3.65). Concordance of sequences from the second hypervariable region (HVR2) of the G gene supported household clustering (97.7% [84/86]).
CONCLUSIONS: Children aged 0-5 years were the main inferred household introducers and were highly susceptible, with infants aged <1 year the most susceptible. Household transmission frequently involved spread from children aged 0-5 years to adults, supporting age-targeted household prevention.