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

Objectives: To summarise the major types of SARS-CoV-2 cluster infections worldwide through a comprehensive systematic review. Methods: All studies published between 01 January-15 June 2020 on COVID-19 cluster infections in English electronic databases were searched, including PubMed, Embase, Web of Knowledge, and Scopus. All included studies were independently screened and evaluated by two authors, and information from each study was extracted using a standard form. Results: Sixty-five studies were included, which involved 108 cluster infections from 13 countries, areas or territories. Seventy-two (66.7%) of the cluster infections were reported in China. The major types of cluster infections were families, community transmission, nosocomial infection, gatherings, transportation, shopping malls, conferences, tourists, religious organisations, workers, prisons, offices, and nursing homes. Conclusions: The SARS-CoV-2 can be transmitted in various circumstances, and cluster infections play an important role in the rapid evolution of COVID-19 transmission. Prevention and control measures such as social distancing must be strictly implemented to contain these cluster infections. (C) 2020 The Authors. Published by Elsevier Ltd on behalf of International Society for Infectious Diseases.