Emerging Infectious Diseases (Mar 2021)
Familial Clusters of Coronavirus Disease in 10 Prefectures, Japan, February−May 2020
Abstract
The overall coronavirus disease secondary attack rate (SAR) in family members was 19.0% in 10 prefectures of Japan during February 22–May 31, 2020. The SAR was lower for primary cases diagnosed early, within 2 days after symptom onset. The SAR of asymptomatic primary cases was 11.8%.
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