Research on prevention and control strategies for norovirus clusters: an analysis of epidemiological characteristics and influencing factors of norovirus clusters in Hangzhou, China

Norovirus is currently one of the leading pathogens of infectious diarrhea, imposing a substantial disease burden annually. In recent years, Hangzhou has experienced a year-by-year increase in norovirus clusters across diverse settings, including schools, hospitals, nursing homes, corporations, restaurants, hotels, villages, and construction sites. Individual clusters often affect dozens to hundreds of individuals, indicating persistent gaps in certain aspects of prevention and control efforts. Under constraints of funding and human resources, public health authorities must identify factors warranting prioritized intervention based on their socioeconomic impact. We analyzed 432 norovirus clusters in Hangzhou from 2018 to 2023 and identified transmission route, urban-rural distribution, setting type, and genogroup as key determinants of outbreak scale.The high-incidence period occurs from October to May, during which prevention and control measures should be enhanced. Primary schools and kindergartens are the main settings, with 6.85% of primary schools and 2.63% of kindergartens reporting such clusters. These should be prioritized for targeted interventions. Person-to-person transmission is the dominant route. Strengthening routine environmental disinfection, improving ventilation, and promoting correct handwashing practices among students are essential. Although less common, foodborne transmission leads to larger outbreaks, with more cases, longer duration, and broader classroom impact. Thus, enhanced hygiene supervision of school canteens is critical.Suburban and rural areas, often facing economic and cultural disadvantages, require increased allocation of prevention resources and tailored public health support.