Early epidemiological and clinical manifestations of COVID-19 in Japan

Background: Severe acute respiratory syndrome coronaviruses -2 (SARS-COV2) named as COVID-19 had spread worldwide and leading to 1,210,956 confirmed cases and 67,594 deaths Methods: A data of 1192 confirmed cases and 43 deaths due to COVID-19 in Japan collected from the Ministry of Health, Labour and Welfare of Japan and analysed for different epidemiological parameters and their clinical manifestations. We used Clauset-Newman-Moore (CNM) clustering algorithm to develop web-network of confirmed cases to identified clusters of community transmission. Results: Out of 1192 confirmed cases, 90.60% were symptomatic and 9.39% were asymptomatic. The prevalence of COVID19 in males was 56.29% and 43.20 % in females. The mean interval (SD) from symptom onset to diagnosis was 6-22.6 days while mean interval (SD) from contact to onset of symptoms was 5-19.5 days. People of age range 40-79 were more infected and deaths median age was 80. The main symptoms were fever, dry cough, fatigue and pneumonia. The main infected cities were Tokyo (195/1192, 16.35%), Hokkaido (160/1192 13.42%), Aichi (150/1192, 12.58%) and Osaka (145/1192, 12.16%). Only 2.34% cases had travel history from Wuhan China and Osaka music concert was identify as main cluster for community transmission. While 556 (46.64%) cases were clinically diagnosed and 557 (46.72%) were confirmed by using RT-PCR. Conclusions: Other than, declare emergency Japan need to change their approach of diagnosing COVID-19, as asymptomatic cases prevalence is high and maybe it is reason for current sudden increase of cases. Screening centre should be establish away from hospitals, which are treating positive cases.