Abstract: Objective  To analyze the clinical manifestations and epidemiological characteristics of a cluster case of COVID19 caused by a large religious gathering  in Zhejiang, and to strengthen the awareness  of  the clustering and outbreak epidemic of the COVID19 infection,  so as to effectively control its spread. Methods  21 cases of pneumonia  in the clustered incidence of COVID19 in Zhejiang from January to February 2020 were collected and the clinical and epidemiological characteristics were analyzed  retrospectively. Results  All 21 patients were middleaged and elderly women,  aged (58.94±7.45) years,  10(47.6%)  had basic diseases,  only one patient was diagnosed as a severe case,  and the rest were mild cases, and no patients died during this period. The most common symptoms at the time of onset were fever (19 ［90.5%］),  cough (15［71.4%］),  sputum (9［42.8%］),  rare symptoms included fatigue (1［4.7%］),  diarrhea (1［4.7%］)  and headache (1［4.7%］),  the median time from exposure to disease onset was 7(311.5)  days.  At admission,  albumin  decreased  in  57.14%(12/21),  sodium  decreased in 42.85%(9/21),  urea nitrogen  decreased in  38.09%(8/21),  and lymphopenia  decreased  in  28.57%(6/21). 14.28%(3/21) of patients had decreased potassium and leukocytes. In addition,  patients with elevated blood glucose, Creactive protein,  serum lactate dehydrogenase and transaminase accounted for 61.90%（13/21）, 61.90%（13/21）, 33.33%（7/21）  and  23.80%（5/21）, respectively. All patients had abnormal changes in lung CT examination at admission,  and the  imaging findings were mostly bilateral lung infections with ground glass/spotlike changes. Conclusion  The onset of this cluster case is mainly among  elderly women. Group aggregation can lead to the spread of COVID19,  and the elderly people are more susceptible. Largescale gatherings should be restricted during unusual periods to reduce personnel mobility and contact,  thus contributing to disease control.

Key words: COVID19, cluster incidence, epidemiological study