COVID-19 in the 23 Wards of Tokyo from April 6th to June 14th, 2020

Abstract

Novel coronavirus SARS-CoV-2 disease (COVID-19) has been spreading worldwide after the outbreak in Wuhan, China since December in 2019, and it caused pandemic. As of 15th, June in 2020, in Southeast Asia, the infection of 334 people and none of the death in Vietnam, and in East Asia, 17,439 people were infected and the death of 929 in Japan. In Tokyo, 5,619 (32.2% of all Japan) and 316 people have been infected and dead by COVID-19, respectively. We focused on infection of the virus in Tokyo's 23 wards in Tokyo metropolitan area from April 6th to June 14th. The peak of the infection in the 23 wards of Tokyo was confirmed in the third week in April in 2020, and then the number of the coronavirus infections decreased. The 23 wards can be separated clearly such as Zone 1, 2 and 3 by infectious incidence: Zone 1 downtown, Zone 2 inside of JR-Yamanote Line, and Zone 3 residential areas. The infection was markedly higher in Minato-ku and Sinjuku-ku, at the downtown of Tokyo. On the other hand, the number of infections were higher among young generation and lower among elder generation in the fourth week in April, hereafter the profile has been changed as elder aged infections increased in a V-shaped curve. The initial increase of male infected with the virus in April was due to infection of business commuters of 20s to 70s. After the Tokyo Metropolitan Government declared a state of emergency, the number of people infected decreased, being different for each ward in Tokyo. When bars and clubs were closed, the number of the infected people in Minato-ku at downtown and residential areas was decreased. These results suggest that working persons infected with the novel coronavirus spread the virus at home and social area. Therefore, social distance is required for protection of the infection spreading.