Coronavirus disease 2019 (COVID-19) and influenza may infect a person simultaneously; hence, adequate measures must be prepared for the next winter in Japan. In preparation for the future, this study aimed to clarify the rate of influenza coinfection in patients with COVID-19 in previous winter. We conducted a retrospective study of the medical records of 193 patients diagnosed as having COVID-19 between January 31, 2020, and April 23, 2020, in a single hospital. We measured the rate of coinfection with COVID-19 and influenza. We found no patient was coinfected with influenza using rapid diagnostic testing. The occurrence of coinfection with influenza and COVID-19 seems to be rare in the past winter in Japan.

2019 年冠状病毒病 (COVID-19) 和流感可能同时感染一个人；因此，必须为日本的下一个冬天准备充分的措施。为未来做准备，本研究旨在阐明去年冬天 COVID-19 患者的流感合并感染率。我们对 2020 年 1 月 31 日至 2020 年 4 月 23 日期间在一家医院诊断为 COVID-19 的 193 名患者的病历进行了回顾性研究。我们测量了 COVID-19 和流感的合并感染率。我们使用快速诊断测试发现没有患者同时感染流感。在日本过去的冬天，流感和 COVID-19 合并感染的发生似乎很少见。