Cluster infections play important roles in the rapid evolution of COVID-19 transmission: a systematic review

Liu, Tao; Gong, Dexin; Xiao, Jianpeng; Hu, Jianxiong; He, Guanhao; Rong, Zuhua; Ma, Wenjun

OBJECTIVES: To summarize the major types of cluster infections of SARS-CoV-2 all over the world through a comprehensive systematic review. METHODS: We searched all of the studies published between January 1, 2020 and June 15, 2020, on the cluster infections of COVID-19 in the English electronic databases including PubMed, Embase, Web of Knowledge, and Scopus. All included studies were independently screened and evaluated by two authors, and information of each study was extracted using a standard form. RESULTS: A total of 65 studies were included in this study which involved 108 cluster infections from 13 countries, areas or territories. Out of the cluster infections, 72(66.7%) were reported in China. The major types of cluster infections include family cluster, community transmission, nosocomial infection, transmission in gathering activities, on transportations, in shopping malls, on conference, among tourists, in religious organizations, among workers, in prisons, office, and in nursing home. CONCLUSIONS: The SARS-CoV-2 can be transmitted in various circumstances, and cluster infection plays important roles in the rapid evolution of COVID-19 transmission. Prevention and control measures such as social distance must be strictly implemented to contain the cluster infections.