Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand.
Department of International Health, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, United States of America.
PLoS One. 2021 Apr 1;16(4):e0238088. doi: 10.1371/journal.pone.0238088. eCollection 2021.
COVID-19 seroprevalence data, particularly in less developed countries with a relatively low incidence, has been scant. We aimed to explore the seroprevalence of hospital staff in the area with zero confirmed COVID-19 case to shed light on the situation of COVID-19 infection in zero or low infection rate countries where mass screening was not readily available.
A locally developed rapid immunoglobulin M (IgM)/immunoglobulin G (IgG) test kit was used for hospital staff screening of Ranong hospital which is located in a province with zero COVID-19 prevalence in Thailand from 17th April to 17th May 2020. All staff was tested, 100 of which were randomly invited to have a repeating antibody test in one month. (Thai Clinical Trials Registry: TCTR20200426002).
Of 844 hospital staff, 82 were tested twice one month apart (response rate for repeating antibody test 82%). Overall, 0.8% of the participants (7 of 844) had positive IgM, none had positive IgG. Female staff had 1.0% positive IgM (95% CI: 0.5-2.1%) while male had 0.5% positive IgM (95% CI: 0.1-2.6%). No participants with a history of travel to the high-risk area or close contact with PCR-confirmed COVID-19 case developed SARS-CoV-2 antibodies. Among 844 staff, 811 had no symptoms and six of them developed IgM seropositive (0.7%) while 33 had minor symptoms and only one of them developed IgM seropositive (3.0%). No association between SARS-CoV-2 IgM status and gender, history of travel to a high-risk area, close contact with PCR-confirmed or suspected COVID-19 case, presence of symptoms within 14 days, or previous PCR status was found. None of the hospital staff developed SARS-CoV-2 IgG.
COVID-19 antibody test could detect a considerable number of hospital staff who could be potential silent spreaders in a province with zero COVID-19 cases. Accurate antibody testing is a valuable screening tool, particularly in asymptomatic healthcare workers. Trial registration: This study was approved by the Institutional Review Board of Chulalongkorn University (IRB No.236/63) and the Institutional Review Board of Ranong Hospital. (Thai Clinical Trials Registry: TCTR20200426002).
COVID-19 血清流行率数据，特别是在发病率相对较低的欠发达国家，非常有限。我们旨在探索零确诊 COVID-19 病例地区医院工作人员的血清流行率，以了解在大规模筛查不易获得的零感染或低感染率国家 COVID-19 感染情况。
2020 年 4 月 17 日至 5 月 17 日，在泰国一个没有 COVID-19 流行的省份，我们使用当地开发的快速免疫球蛋白 M（IgM）/免疫球蛋白 G（IgG）检测试剂盒对拉廊医院的医院工作人员进行筛查。所有工作人员都接受了检测，其中 100 人被随机邀请在一个月后重复进行抗体检测。（泰国临床试验注册处：TCTR20200426002）。
在 844 名医院工作人员中，有 82 人在一个月后接受了两次检测（重复抗体检测的应答率为 82%）。总体而言，参与者中有 0.8%（7/844）的 IgM 呈阳性，没有 IgG 呈阳性。女性工作人员的 IgM 阳性率为 1.0%（95%CI：0.5-2.1%），而男性为 0.5%（95%CI：0.1-2.6%）。没有出现过前往高危地区旅行或与经 PCR 确诊的 COVID-19 病例有密切接触史的参与者产生 SARS-CoV-2 抗体。在 844 名工作人员中，811 名没有症状，其中 6 名出现 IgM 阳性（0.7%），33 名出现轻微症状，只有 1 名出现 IgM 阳性（3.0%）。SARS-CoV-2 IgM 状态与性别、前往高危地区旅行史、与经 PCR 确诊或疑似 COVID-19 病例的密切接触史、14 天内出现症状以及之前的 PCR 状态均无关联。没有医院工作人员出现 SARS-CoV-2 IgG。
COVID-19 抗体检测可以检测到相当数量的医院工作人员，他们可能是零 COVID-19 病例省份中的潜在隐性传播者。准确的抗体检测是一种有价值的筛查工具，特别是在无症状的医护人员中。试验注册：本研究得到朱拉隆功大学机构审查委员会（IRB 编号 236/63）和拉廊医院机构审查委员会的批准。（泰国临床试验注册处：TCTR20200426002）。
