Abstract: Objective By investigating an outbreak of norovirus infection reported by a university in Haidian District of Beijing on December 27,2019,to analyze the risk factors,and provide reference basis for effective control of the epidemic. Methods The basic situation,suspected cases and canteen staff of a university where the epidemic occurred were investigated and analyzed in detail by using field epidemiological methods and descriptive analysis methods. At the same time,samples were collected for laboratory testing and statistical analysis. Results From December 23,2019 to 2020,January 9th,2020,the University reported 389 suspected cases of acute gastroenteritis,with a total incidence rate of 0.69%,distributed in 42 dormitory buildings. The difference in incidence between males and females was statistically significant（χ²=24.719,P<0.01）. There were 375 students and 14 teaching workers,and the difference in incidence between students and teaching workers was statistically significant（χ²=67.088, P<0.01）. A total of 1 173 samples of cases,close contacts and canteen staff were collected. 169 positive samples of norovirus GⅡwere detected,with a positive rate of 14.41%,and 6 positive samples of norovirus GⅠwere detected,with a positive rate of 0.51%. Of 233 environmental samples,six positive samples of norovirus GⅡwere detected,and the positive rate was 2.56%. The samples with norovirus GⅡwere typed,and all genotypes were GⅡ.2[P16]. Among 517 canteen employees,the difference in the positive detection was statistically significant between gender groups（χ²=5.628,P<0.05）. The epidemic situation was controlled in time through effective prevention and control measures such as isolation of canteen staff with cases and latent infection,temporary closure of canteens with serious pollution,strengthening the concentration and frequency of key environmental disinfection,carrying out personal protection knowledge training,and standardized treatment of excreta and vomit. Conclusions According to the field epidemiological investigation,clinical manifestations and laboratory test results,it is determined that the event is an outbreak of norovirus GⅡ.2[P16] caused by multi-channel transmission. It is necessary to strengthen the publicity and training of norovirus prevention and control among teachers and students,strengthen the health monitoring of key groups such as canteens,standardize disinfection,so as to eliminate and prevent the occurrence or spread of norovirus outbreak in colleges and universities.

Key words: Norovirus, Outbreak, Investigation and analysis, Standardize disinfection, Health monitoring