Global Health & Medicine 2021;3(4):236-239.

A single-center descriptive study of untraced sources of infection among new cases of coronavirus disease in Tokyo, Japan

Hikida S, Morioka S, Fujii N, Tajima T, Terayama Y, Sugiura Y, Ishikane M, Takasaki J, Hojo M, Ohmagari N


We investigated possible sources of newly infected patients with coronavirus disease (COVID-19) after the fourth wave in order to explore unknown sources. Retrospective chart review on all the confirmed patients with COVID-19 admitted to the National Center for Global Health and Medicine (NCGM) in Tokyo, Japan was conducted from May 22 through June 29, 2021. Among the 22 participants, 14 (64%) had a history of known highrisk infection behaviors. Of those, 12 reported that their activities involved eating and drinking. In addition, there were 24 high-risk situations, of those, 21 (88%) were related to indoor dining, and masks were not worn in 22 situations (92%). New source of infection has not been identified. In situations with a high known risk of infection, many cases were related to eating and drinking, and insufficient use of masks was evident. Raising risk awareness on infection prevention and control of COVID-19 is urgently needed.

KEYWORDS: coronavirus disease, untraced sources of infection, high-risk infection behavior, indoor dining, mask

DOI: 10.35772/ghm.2021.01092

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