This retrospective study evaluated stored nasopharyngeal swab samples from Japanese patients with influenza-like illness during the 2019/2020 season. We aimed to determine whether COVID-19 had spread in the community before the first confirmed case. The period of influenza season during 2019/2020 in Nagasaki was shorter than in previous influenza seasons. When the first COVID-19 case was reported in Nagasaki prefecture, the number of influenza cases were very low. No positive results for SARS-CoV-2 were detected in 182 samples that were obtained from adult outpatients. Our results revealed no large-scale spread of COVID-19 in the community before the first confirmed case.

这项回顾性研究评估了 2019/2020 季节日本流感样疾病患者的鼻咽拭子样本。我们的目标是确定在第一例确诊病例之前 COVID-19 是否已在社区中传播。长崎 2019/2020 年的流感季节比以往的流感季节短。当长崎县报告第一例 COVID-19 病例时，流感病例数非常低。在从成人门诊获得的 182 份样本中，未检测到 SARS-CoV-2 阳性结果。我们的结果显示，在第一例确诊病例之前，COVID-19 在社区中没有大规模传播。