Increased Secondary Attack Rate among Unvaccinated Household Contacts of Coronavirus Disease 2019 Patients with Delta Variant in Japan

International Journal of Environmental Research and Public Health

Koji Wada¹  Hideo Tanaka²  Kazue Mukouyama³  Natsumi Osaki³  Tsuyoshi Ogata³  Yumiko Nozawa³  Emiko Tanaka³  Etsuko Noguchi³  Kayoko Seo³ 

[1] Department of Public Health, Faculty of Medicine and Graduate School of Public Health, International University of Health and Welfare, Tokyo 107-8402, Japan;Fujiidera Public Health Center of Osaka Prefectural Government, Fujiidera 583-0024, Japan;Itako Public Health Center of Ibaraki Prefectural Government, Itako 311-2422, Japan;

关键词: COVID-19;    SARS-CoV-2;    Delta variant;    Alpha variant;    household transmission;    secondary attack rate;   

DOI  :  10.3390/ijerph19073889

来源: DOAJ

【 摘 要 】

This study aimed to elucidate the household secondary attack rate (HSAR) of the Delta variant in comparison to the Alpha variant, and evaluate the risk factors among unvaccinated household contacts of patients with coronavirus disease 2019 (COVID-19). We studied household contacts of index cases of COVID-19 infected with Delta (L452R mutation), Alpha (N501Y mutation), and wild strain from December 2020 through November 2021 in Itako, Japan. The HSARs of the entire household contact, and the contact of index case with Delta variant were calculated and compared across the risk factors. We used a generalized estimating equation regression model for the multivariate analysis. We enrolled 1257 unvaccinated contacts from 580 households. The HSAR was higher in household contacts of index patients with Delta (48.5%) than with Alpha variant (21.7%) (aOR = 3.34, p = 0.000). In Delta variants, the HSAR was higher in household contacts with spousal relationships to index patients (63.4%) than contacts with other relationships (45.5%) (aOR 1.94, p = 0.026), and was lower in household contacts of index patients aged ≤19 (33.1%) than for contacts of index cases aged 20–59 years (52.6%) (aOR = 0.50, p = 0.027). The result of our study can be used to devise informed strategy to prevent transmission within households.

【 授权许可】

Unknown