Clusters of Coronavirus Disease in Communities, Japan, January–April 2020
Yuki Furuse, Eiichiro Sando, Naho Tsuchiya, Reiko Miyahara, Ikkoh Yasuda, Yura K Ko, Mayuko Saito, Konosuke Morimoto, Takeaki Imamura, Yugo Shobugawa, Shohei Nagata, Kazuaki Jindai, Tadatsugu Imamura, Tomimasa Sunagawa, Motoi Suzuki, Hiroshi Nishiura, Hitoshi Oshitani
Abstract
C oronavirus disease (COVID-19) typically causes febrile illness with respiratory symptoms (1,2), and many countries worldwide have been affected. Before characterizing COVID-19 as a pandemic in March 2020 (3), the World Health Organization advised countries to take measures to reduce spread of the virus, including identifying cases and clusters, isolating patients, tracing contacts, and preventing community transmission (4). Several countries have reported on the characteristics of a small number of clusters of COVID-19 cases (5,6). However, few comprehensive reports provide an overview of clusters of COVID-19 cases in communities and the significance of such clusters. We analyzed 61 COVID-19 clusters among various communities in Japan and identified 22 probable primary cases that might have contributed to the disease incidence in clusters.