Global Health & Medicine
Online ISSN : 2434-9194
Print ISSN : 2434-9186
Correspondence
A low proportion of asymptomatic COVID-19 patients with the Delta variant infection by viral transmission through household contact at the time of confirmation in Ibaraki, Japan
Tsuyoshi OgataHideo TanakaFujiko IrieYumiko NozawaEtsuko NoguchiKayoko SeoEmiko Tanaka
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2022 Volume 4 Issue 3 Pages 192-196

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Abstract

We conducted a study to investigate the proportion of patients with asymptomatic coronavirus disease 2019 (COVID-19) infected with the Delta variant compared with those infected with the wild-type strain at the time of confirmation. A total of 504 patients with confirmed severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection by viral transmission through household contact in Ibaraki, Japan were included. The proportion of asymptomatic COVID-19 patients at the time of confirmation was compared between patients infected with L452R mutation strain from June to September 2021 and those infected with the wild-type strain from November 2020 to January 2021, and was found to be 14.2% and 28.8%, respectively (relative risk, 0.49; 95% confidence interval, 0.35-0.70). The proportion of asymptomatic COVID-19 patients by viral transmission through household contact was lower among the Delta variant than those among the wild-type strain at the time of confirmation. It might contribute to attenuation of transmission.

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© 2022 National Center for Global Health and Medicine
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