Positive Ratio of Polymerase Chain Reaction (PCR) and Validity of Pre-Screening Criteria at an Outpatient Screening Center during the Early Phase of the COVID-19 Epidemic in Japan

Despite the increase in COVID-19 cases worldwide, the number of cases in Japan has been relatively low, and an explosive surge in the prevalence has not occurred. Since March 2020, the Ministry of Health, Labour and Welfare (MHLW) in Japan recommended original criteria for considering polymerase chain reaction (PCR) testing, although there was a lack of clear evidence for appropriate targets for COVID-19 testing. This study aimed to evaluate COVID-19 positive ratio and pre-screening criteria in Tokyo immediately after insurance-covered SARS-CoV-2 polymerase chain reaction testing became available in Japan. We tested 277 individuals (positive: 9.0%) from March 9-29, 2020. In total, 277 patients with mild symptoms in metropolitan Tokyo underwent SARS-CoV-2 PCR testing. The results revealed that 25 (9.0%) patients were PCR positive. The sensitivity and specificity of the MHLW criteria were 100% and 10.7%, respectively. When the criteria excluded nonspecific symptoms, fatigue, and dyspnea, sensitivity slightly decreased to 92%, and specificity increased to 22.2%. Specificity was highest when the fever criterion was ≥37.5°C for ≥4 days, and exposure/travel history, including age and underlying comorbidities, was considered. Our findings suggest that MHLW criteria, including symptoms and exposure/travel history, could support COVID-19 pre-screening.