Coronavirus infection 2019 (COVID-19) is a respiratory infection caused by a novel coronavirus (SARS-CoV-2) that was first reported in Wuhan, China, in December 2019. In Japan, since mid-February 2020, there have been a series of reports of COVID-19 outbreaks among people without apparent contact with COVID-19 patients or visitors to Japan from endemic areas, or a recent history of visiting an endemic area. We encountered a patient with COVID-19 arising from local community transmission of infection, who presented with the chief complaints of fatigue and anorexia. In this patient, a quantitative polymerase chain reaction (PCR) assay showed a higher viral load and a more extended period of viral excretion in nasopharyngeal swab specimens than in pharyngeal swab specimens. When using a PCR assay as a diagnostic test or as an indicator of improvement, we should be aware of the characteristics and limitations of the test.
