As a response to the coronavirus disease 2019 (COVID-19) pandemic, Vietnam enforced strict quarantine, contact tracing and physical distancing policies resulting in one of the lowest numbers of individuals infected with severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) globally. This study aimed to determine the prevalence of SARS-CoV-2 antibody positivity among high-risk populations in Vietnam. A prevalence survey was undertaken within four communities in Vietnam, where at least two COVID-19 cases had been confirmed. Participants were classified according to the location of exposure: household contacts, close contacts, community members, and healthcare workers (HCWs) responsible for treating COVID-19 cases. Participants completed a baseline questionnaire and SARS-CoV-2 IgG antibodies were quantified using a commercial assay. A total of 3049 community members and 149 health care workers consented to the study. Among 13 individuals who were seropositive (0.4%), five household contacts (5/27, 18.5%), one close contact (1/53, 1.9%), and seven community members (7/2954, 0.2%) had detectable SARS-CoV-2 antibodies. All HCWs were negative for SARS-CoV-2 antibodies. Participants were tested a median of 15.1 (interquartile range from 14.9 to 15.2) weeks after exposure. Our study found a low prevalence of SARS-CoV-2 antibodies in high-risk communities and healthcare workers in communities in Vietnam with known COVID-19 cases.

中文翻译：

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越南高危人群中 SARS-CoV-2 抗体的血清流行率

作为对 2019 年冠状病毒病 (COVID-19) 大流行的回应，越南实施了严格的隔离、接触者追踪和物理疏远政策，导致感染严重急性呼吸系统综合症冠状病毒 2 (SARS-CoV- 2）全球。本研究旨在确定越南高危人群中 SARS-CoV-2 抗体阳性的流行情况。在越南的四个社区内进行了一项流行率调查，其中至少确认了两个 COVID-19 病例。参与者根据接触地点进行分类：家庭接触者、密切接触者、社区成员和负责治疗 COVID-19 病例的医护人员 (HCW)。参与者完成了一份基线问卷，并使用商业化验对 SARS-CoV-2 IgG 抗体进行了量化。共有 3049 名社区成员和 149 名卫生保健工作者同意这项研究。在血清阳性的 13 人 (0.4%) 中，5 名家庭接触者 (5/27, 18.5%)、1 名密切接触者 (1/53, 1.9%) 和 7 名社区成员 (7/2954, 0.2%) 检测到 SARS -CoV-2 抗体。所有医护人员的 SARS-CoV-2 抗体均呈阴性。参与者在暴露后接受测试的中位数为 15.1（四分位距为 14.9 至 15.2）周。我们的研究发现，在越南已知 COVID-19 病例的高风险社区和医护人员中，SARS-CoV-2 抗体的流行率较低。2%) 具有可检测的 SARS-CoV-2 抗体。所有医护人员的 SARS-CoV-2 抗体均呈阴性。参与者在暴露后接受测试的中位数为 15.1（四分位距为 14.9 至 15.2）周。我们的研究发现，在越南已知 COVID-19 病例的高风险社区和医护人员中，SARS-CoV-2 抗体的流行率较低。2%) 具有可检测的 SARS-CoV-2 抗体。所有医护人员的 SARS-CoV-2 抗体均呈阴性。参与者在暴露后接受测试的中位数为 15.1（四分位距为 14.9 至 15.2）周。我们的研究发现，在越南已知 COVID-19 病例的高风险社区和医护人员中，SARS-CoV-2 抗体的流行率较低。