In early 2020, Japan repatriated 566 nationals from China. Universal laboratory testing and 14-day monitoring of returnees detected 12 cases of severe acute respiratory syndrome coronavirus 2 infection; initial screening results were negative for 5. Common outcomes were remaining asymptomatic (n = 4) and pneumonia (n = 6). Overall, screening performed poorly.
Keywords: 2019 novel coronavirus disease; Asymptomatic infections; COVID-19; SARS-CoV-2; bias; coronavirus disease; pneumonia; prevalence; quarantine; respiratory infections; severe acute respiratory syndrome coronavirus 2; viruses; zoonoses.