2020 年 94 巻 4 号 p. 591-595
Real-time polymerase chain reaction (RT-PCR) assay is used for the diagnosis of novel coronavirus disease 2019 (COVID-19), and for identifying those patients with COVID-19 who have recovered but may require ongoing isolation. We report two cases of COVID-19 in whom the RT-PCR test remained persistently positive until 16 and 19 days after resolution of the symptoms (33 and 28 days after the onset of symptoms), respectively. While the viral load in the respiratory specimens had decreased after resolution of the symptoms, the RT-PCR test result continued to be positive. Mucoid sputum samples obtained by handing containers to the patient returned positive results for even longer periods than nasal swab samples. Our findings have led us to question the usefulness of the RT-PCR assay for determining the appropriate time to release patients from isolation after they show symptomatic recovery. RT-PCR performed using mucoid sputum samples was also sensitive and safe, because of the low exposure of the healthcare workers to the virus while collecting the test samples.
Both authors contributed equally to this study.