Department of Microbiology and Cell Biology, Tokyo Metropolitan Institute of Medical Science.
Department of Clinical Laboratory, and, Graduate School of Medicine the University of Tokyo Hospital.
J Epidemiol. 2022 Feb 5;32(2):105-111. doi: 10.2188/jea.JE20210324. Epub 2021 Dec 17.
Tokyo, the capital of Japan, is a densely populated city of >13 million people, so the population is at high risk of epidemic severe acute respiratory coronavirus 2 (SARS-CoV-2) infection. A serologic survey of anti-SARS-CoV-2 IgG would provide valuable data for assessing the city's SARS-CoV-2 infection status. Therefore, this cross-sectional study estimated the anti-SARS-CoV-2 IgG seroprevalence in Tokyo.
Leftover serum of 23,234 hospital visitors was tested for antibodies against SARS-CoV-2 using an iFlash 3000 chemiluminescence immunoassay analyzer (Shenzhen YHLO Biotech, Shenzhen, China) with an iFlash-SARS-CoV-2 IgG kit (YHLO) and iFlash-SARS-CoV-2 IgG-S1 kit (YHLO). Serum samples with a positive result (≥10 AU/mL) in either of these assays were considered seropositive for anti-SARS-CoV-2 IgG. Participants were randomly selected from patients visiting 14 Tokyo hospitals between September 1, 2020 and March 31, 2021. No participants were diagnosed with coronavirus disease 2019 (COVID-19), and none exhibited COVID-19-related symptoms at the time of blood collection.
The overall anti-SARS-CoV-2 IgG seroprevalence among all participants was 1.83% (95% confidence interval [CI], 1.66-2.01%). The seroprevalence in March 2021, the most recent month of this study, was 2.70% (95% CI, 2.16-3.34%). After adjusting for population age, sex, and region, the estimated seroprevalence in Tokyo was 3.40%, indicating that 470,778 individuals had a history of SARS-CoV-2 infection.
The estimated number of individuals in Tokyo with a history of SARS-CoV-2 infection was 3.9-fold higher than the number of confirmed cases. Our study enhances understanding of the SARS-CoV-2 epidemic in Tokyo.
日本首都东京是一个人口超过 1300 万的人口稠密城市，因此人口面临严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）感染的高风险。对 SARS-CoV-2 抗 IgG 的血清学调查将为评估城市 SARS-CoV-2 感染状况提供有价值的数据。因此，本横断面研究估计了东京的 SARS-CoV-2 抗 IgG 血清流行率。
使用 iFlash 3000 化学发光免疫分析仪（中国深圳宇恒生物科技有限公司）和 iFlash-SARS-CoV-2 IgG 试剂盒（宇恒）和 iFlash-SARS-CoV-2 IgG-S1 试剂盒（宇恒）对 23234 名医院访客的剩余血清进行 SARS-CoV-2 抗体检测。在这两种检测方法中，任何一种检测结果呈阳性（≥10 AU/mL）的血清样本均被认为对 SARS-CoV-2 IgG 呈血清阳性。参与者是从 2020 年 9 月 1 日至 2021 年 3 月 31 日期间访问东京 14 家医院的患者中随机选择的。没有参与者被诊断为 2019 年冠状病毒病（COVID-19），并且在采血时没有表现出与 COVID-19 相关的症状。
所有参与者的 SARS-CoV-2 抗 IgG 总体血清流行率为 1.83%（95%置信区间[CI]，1.66-2.01%）。本研究最近的 2021 年 3 月的血清流行率为 2.70%（95%CI，2.16-3.34%）。在调整人口年龄、性别和地区后，东京的估计血清流行率为 3.40%，表明有 470778 人有 SARS-CoV-2 感染史。
估计东京有 SARS-CoV-2 感染史的人数是确诊病例数的 3.9 倍。我们的研究增强了对东京 SARS-CoV-2 流行情况的理解。
