BACKGROUND: As an emerging infectious disease, COVID-19 has involved with many countries and regions. With the further development of the epidemic, the proportion of clusters has been increased. METHODS: In our study, we collected the information of COVID-19 clusters in Qingdao City. The epidemiological characteristic and clinical manifestation were analyzed. RESULTS: 11 clusters of COVID-19 were reported in Qingdao City during Jan 29, 2020 and Feb 23, 2020, involved 44 confirmed cases, which were accounted for 73.33% of all confirmed cases. Most from Jan 19 and Feb 2, 2020, the cases mainly concentrated in the district which had many designated hospitals. The cases aged 20-59 years old accounted for the largest proportion (68.18%), with the male-to-female sex ration 0.52:1. Three cases were infected from exposure to confirmed cases. The average incubation period was 6.28d. The median number of cases per cluster was 4 and the median duration time was 6d. The median cumulative number of exposure persons was 53. CONCLUSION: More attention should be paid on the epidemic of clusters in prevention and control of COVID-19. Besides isolating patients, it is essential to track, screen and isolate the close contacts. Self-isolation is the key especially for healthy people in epidemic area.
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