An Outbreak of Norovirus in a Long-term Care Facility — Guangzhou City, Guangdong Province, China, December 2024

Background This acute gastroenteritis outbreak represents the most extensive norovirus cluster reported in Guangzhou long-term care facilities in recent years. In order to control the outbreak, an epidemiological investigation was conducted to determine the causative agent, sources, role of transmission and risk factors of the infections while providing technical guidance to the institution for implementing infection control measures. Methods An epidemiological investigation was carried out for cases among elderly residents and staff members in the long-term care facility. A case-control study was conducted. Information on basic demographic characteristics, clinical presentations, exposure history, care giving interactions, off-site activities, participation in congregate events, kitchen staff health status, food hygiene, and drinking water hygiene was collected. Multivariate analysis was used to analyze risk factors. Rectal swabs of the cases and staff members, as well as environmental samples were collected to detect potential viruses and bacteria. Genotyping and environmental surveillance were implemented to delineate transmission pathways. Results The overall attack rate was 17.72% (126/711), including 554 elderly residents and 157 staff members. Key risk factors included requiring partial dressing assistance (adjusted odds ratio [ aOR ] = 1.92, 95% confidence interval [CI] : 1.06, 3.64), sharing dining tables with cases during meals ( aOR  = 2.47, 95% CI : 1.54, 3.99), co-residing in dormitories with cases ( aOR  = 2.58, 95% CI : 1.60, 4.17), off-site engagements during the pre-outbreak period (December 18–24) ( aOR  = 86.03, 95% CI : 17.44, 2076.65). Genotype analysis confirmed norovirus GII.17[P17] in both caregivers and residents. Conclusions Our findings underscore the necessity of implementing infection control strategies, including early "Relative Static Management", rigorous enforcement of environmental disinfection and strict enforcement of caregivers compliance with personal protective equipment use in long-term care facilities.