Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19)
Citation: Hiroshi Nishiura, Hitoshi Oshitani, Tetsuro Kobayashi, Tomoya Saito, Tomimasa Sunagawa, Tamano Matsui, Takaji Wakita, MHLW COVID-19 Response Team, Motoi Suzuki Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19).
Investigated 110 cases from 11 clusters, all associated with close contact in indoor spaces. 27 of the 110 were primary cases that generated secondary cases. The odds that a primary case transmitted COVID-19 in a closed environment was 18.7 times greater compared to an open-air environment. Nine of 11 "superspreading" (to more than 3 people) events took place in closed spaces.