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. 2021 Jul-Sep:11:100747.
doi: 10.1016/j.cegh.2021.100747. Epub 2021 Apr 19.

Estimation of seroprevalence of novel coronavirus disease (COVID-19) using preserved serum at an outpatient setting in Kobe, Japan: A cross-sectional study

Asako Doi  1   2 , Kentaro Iwata  3 , Hirokazu Kuroda  1   2 , Toshikazu Hasuike  1   2 , Seiko Nasu  1   4 , Aya Kanda  4 , Tomomi Nagao  4 , Hiroaki Nishioka  2 , Keisuke Tomii  5 , Takeshi Morimoto  6 , Yasuki Kihara  7
Affiliations

Estimation of seroprevalence of novel coronavirus disease (COVID-19) using preserved serum at an outpatient setting in Kobe, Japan: A cross-sectional study

Asako Doi et al. Clin Epidemiol Glob Health. 2021 Jul-Sep.

Abstract

Objectives: Coronavirus disease 2019 (COVID-19) pandemic caused by SARS-CoV-2 has been affecting many people on earth and our society. Japan is known to have relatively smaller number of its infections as well as deaths among developed nations. However, accurate prevalence of COVID-19 in Japan remains unknown. Therefore, we conducted a cross-sectional study to estimate seroprevalence of SARS-CoV-2 infection.

Methods: We conducted a cross-sectional serologic testing for SARS-CoV-2 antibody using 1000 samples from patients at outpatient settings who visited the clinic from March 31 to April 7, 2020, stratified by the decade of age and sex.

Results: There were 33 positive IgG among 1000 serum samples (3.3%, 95%CI: 2.3-4.6%). By applying this figure to the census of Kobe City (population: 1,518,870), it is estimated that the number of people with positive IgG be 50,123 (95%CI: 34,934-69,868). Age and sex adjusted prevalence of positivity was calculated 2.7% (95%CI: 1.8-3.9%), and the estimated number of people with positive IgG was 40,999 (95%CI: 27,333-59,221). These numbers were 396 to 858-fold more than confirmed cases with PCR testing in Kobe City.

Conclusions: Our cross-sectional serological study suggests that the number of people with seropositive for SARS-CoV-2 infection in Kobe, Japan is far more than the confirmed cases by PCR testing.

Keywords: Coronavirus disease 2019 (COVID-19); SARS-CoV-2; Seroprevalence.

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References

    1. Saito T. The Japan Times; 2020. The Secret of Japan's Success in Combating COVID-19 [Internet]https://www.japantimes.co.jp/opinion/2020/06/02/commentary/japan-comment... [cited 2020 October 20]. Available from.
    1. Ministry of Health and Labor of Japan Situation update on June 13, 2020, on coronavirus diseases. 2019. https://www.mhlw.go.jp/stf/newpage_14241.html in Japanese. Viewed on.
    1. Omori R., Mizumoto K., Chowell G. Changes in testing rates could mask the novel coronavirus disease (COVID-19) growth rate. Int J Infect Dis. 2020;94:116–118. - PMC - PubMed
    1. Japan PM Abe Declares State of Emergency amid Widespread Virus Infections [Internet] Kyodo News+; 2020 Oct 20. https://english.kyodonews.net/news/2020/04/ac4415709921-abe-to-declare-s... Available from.
    1. Nishiura H., Oshitani H., Kobayashi T., et al. Closed environments facilitate secondary transmission of coronavirus disease 2019 (COVID-19) medRxiv. 2020 Mar 3 2020.02.28.20029272.