Had COVID-19 spread in the community before the first confirmed case in Nagasaki, Japan?

Norihito Kaku; Kenji Ota; Daisuke Sasaki; Norihiko Akamatsu; Naoki Uno; Kei Sakamoto; Kosuke Kosai; Hiroo Hasegawa; Koichi Izumikawa; Hiroshi Mukae; Katsunori Yanagihara

doi:10.1016/j.micinf.2021.104812

Had COVID-19 spread in the community before the first confirmed case in Nagasaki, Japan?

Microbes Infect. 2021 May-Jun;23(4-5):104812. doi: 10.1016/j.micinf.2021.104812. Epub 2021 Mar 27.

Authors

Affiliations

¹ Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, Japan; Department of Laboratory Medicine, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan. Electronic address: norihitk@gmail.com.
² Department of Laboratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, Japan; Department of Laboratory Medicine, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan.
³ Department of Laboratory Medicine, Nagasaki University Hospital, 1-7-1 Sakamoto, Nagasaki, Japan.
⁴ Department of Infectious Diseases, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, Japan.
⁵ Department of Respiratory Medicine, Nagasaki University Graduate School of Biomedical Sciences, 1-7-1 Sakamoto, Nagasaki, Japan.

Abstract

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.

Keywords: COVID-19; Influenza; RT-PCR; SARS-CoV-2.

MeSH terms

COVID-19 / diagnosis*
COVID-19 / epidemiology*
COVID-19 Nucleic Acid Testing
Humans
Influenza, Human / epidemiology
Japan / epidemiology
Retrospective Studies
SARS-CoV-2 / isolation & purification