Sentinel Surveillance of COVID-19: The Importance of Epidemiologic Concepts and Reasoning - Yuzo Arima; Takuri Takahashi; Ayu Kasamatsu; Takeshi Arashiro; Yusuke Kobayashi; Miyako Otsuka; Osamu Takahara; Reiko Shimbashi; Katsuhiro Komase; Taro Kamigaki; Motoi Suzuki (Journal of Epidemiology)