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Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan

This study investigated the household secondary attack rate (HSAR) of patients with coronavirus disease (COVID-19) during the omicron variant-dominant period. The HSAR of COVID-19 cases during the omicron variant-dominant period (4–20 January 2022) was calculated and compared with the delta variant-...

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Autores principales: Ogata, Tsuyoshi, Tanaka, Hideo, Tanaka, Emiko, Osaki, Natsumi, Noguchi, Etsuko, Osaki, Yukino, Tono, Ayane, Wada, Koji
Formato: Online Artículo Texto
Lenguaje:English
Publicado: MDPI 2022
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9266248/
https://www.ncbi.nlm.nih.gov/pubmed/35805724
http://dx.doi.org/10.3390/ijerph19138068
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author Ogata, Tsuyoshi
Tanaka, Hideo
Tanaka, Emiko
Osaki, Natsumi
Noguchi, Etsuko
Osaki, Yukino
Tono, Ayane
Wada, Koji
author_facet Ogata, Tsuyoshi
Tanaka, Hideo
Tanaka, Emiko
Osaki, Natsumi
Noguchi, Etsuko
Osaki, Yukino
Tono, Ayane
Wada, Koji
author_sort Ogata, Tsuyoshi
collection PubMed
description This study investigated the household secondary attack rate (HSAR) of patients with coronavirus disease (COVID-19) during the omicron variant-dominant period. The HSAR of COVID-19 cases during the omicron variant-dominant period (4–20 January 2022) was calculated and compared with the delta variant-dominant period (20 August to 7 November 2021) in Itako, Japan. In Itako, all 47 and 119 samples tested during the omicron and delta variant-dominant periods were negative and positive, respectively, for the L452R mutation. We used a generalized estimating equation regression model. The HSAR was 31.8% (95% confidence interval (CI) 27.7–36.2) for 456 household contacts during the omicron variant-dominant period; it was higher than that during the delta variant-dominant period (25.2%) (adjusted risk ratio [aRR] 1.61, CI 1.13–2.28). During the omicron variant-dominant period, HSAR was lower for the household contacts of completely vaccinated index patients (27.3%) than for contacts of other index patients (41.2%) (vaccine effectiveness for infectee 0.43, 95% CI 0.16–0.62) and was significantly higher for female contacts than for male contacts (36.2% vs. 26.1%; aRR 1.29, 95% CI 1.01–1.65). The HSAR was significantly higher during the omicron variant-dominant period than the delta variant-dominant period. The vaccination of index patients might protect household contacts.
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spelling pubmed-92662482022-07-09 Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan Ogata, Tsuyoshi Tanaka, Hideo Tanaka, Emiko Osaki, Natsumi Noguchi, Etsuko Osaki, Yukino Tono, Ayane Wada, Koji Int J Environ Res Public Health Article This study investigated the household secondary attack rate (HSAR) of patients with coronavirus disease (COVID-19) during the omicron variant-dominant period. The HSAR of COVID-19 cases during the omicron variant-dominant period (4–20 January 2022) was calculated and compared with the delta variant-dominant period (20 August to 7 November 2021) in Itako, Japan. In Itako, all 47 and 119 samples tested during the omicron and delta variant-dominant periods were negative and positive, respectively, for the L452R mutation. We used a generalized estimating equation regression model. The HSAR was 31.8% (95% confidence interval (CI) 27.7–36.2) for 456 household contacts during the omicron variant-dominant period; it was higher than that during the delta variant-dominant period (25.2%) (adjusted risk ratio [aRR] 1.61, CI 1.13–2.28). During the omicron variant-dominant period, HSAR was lower for the household contacts of completely vaccinated index patients (27.3%) than for contacts of other index patients (41.2%) (vaccine effectiveness for infectee 0.43, 95% CI 0.16–0.62) and was significantly higher for female contacts than for male contacts (36.2% vs. 26.1%; aRR 1.29, 95% CI 1.01–1.65). The HSAR was significantly higher during the omicron variant-dominant period than the delta variant-dominant period. The vaccination of index patients might protect household contacts. MDPI 2022-06-30 /pmc/articles/PMC9266248/ /pubmed/35805724 http://dx.doi.org/10.3390/ijerph19138068 Text en © 2022 by the authors. https://creativecommons.org/licenses/by/4.0/Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
spellingShingle Article
Ogata, Tsuyoshi
Tanaka, Hideo
Tanaka, Emiko
Osaki, Natsumi
Noguchi, Etsuko
Osaki, Yukino
Tono, Ayane
Wada, Koji
Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title_full Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title_fullStr Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title_full_unstemmed Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title_short Increased Secondary Attack Rates among the Household Contacts of Patients with the Omicron Variant of the Coronavirus Disease 2019 in Japan
title_sort increased secondary attack rates among the household contacts of patients with the omicron variant of the coronavirus disease 2019 in japan
topic Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9266248/
https://www.ncbi.nlm.nih.gov/pubmed/35805724
http://dx.doi.org/10.3390/ijerph19138068
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