著者

Aya Sugiyama Fumie Okada Kanon Abe Hirohito Imada Serge Ouoba Bunthen E Md Razeen Ashraf Hussain Masayuki Ohisa Ko Ko Shintaro Nagashima Tomoyuki Akita Shinichi Yamazaki Michiya Yokozaki Eisaku Kishita Junko Tanaka

出版者

The Japanese Society for Hygiene

雑誌

Environmental Health and Preventive Medicine (ISSN:1342078X)

巻号頁・発行日

vol.27, pp.30, 2022 (Released:2022-07-07)

参考文献数

49

被引用文献数

3

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Background: This longitudinal study aimed to determine chronological changes in the seroprevalence of prior SARS-CoV-2 infection, including asymptomatic infections in Hiroshima Prefecture, Japan.Methods: A stratified random sample of 7,500 residents from five cities of Hiroshima Prefecture was selected to participate in a three-round survey from late 2020 to early 2021, before the introduction of the COVID-19 vaccine. The seroprevalence of anti–SARS-CoV-2 antibodies was calculated if at least two of four commercially available immunoassays were positive. Then, the ratio between seroprevalence and the prevalence of confirmed COVID-19 cases in Hiroshima was calculated and compared to the results from other prefectures where the Ministry of Health, Labour and Welfare conducted a survey by using the same reagents at almost the same period.Results: The numbers of participants in the first, second, and third rounds of the survey were 3025, 2396, and 2351, respectively and their anti-SARS-CoV-2 antibodies seroprevalences were 0.03% (95% confidence interval: 0.00–0.10%), 0.08% (0.00–0.20%), and 0.30% (0.08–0.52%), respectively. The ratio between the seroprevalence and the prevalence of confirmed COVID-19 cases in Hiroshima was 1.2, which was smaller than that in similar studies in other prefectures.Conclusions: The seroprevalence of anti–SARS-CoV-2 antibodies in Hiroshima increased tenfold in a half year. The difference between seroprevalence and the prevalence of confirmed COVID-19 cases in Hiroshima was smaller than that in other prefectures, suggesting that asymptomatic patients were more actively detected in Hiroshima.