Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy.
Environ Res. 2021 Apr;195:110793. doi: 10.1016/j.envres.2021.110793. Epub 2021 Jan 27.
Healthcare workers (HCWs) are highly exposed to SARS-CoV-2 infection given their specific tasks. The IgG-IgM serological assay has demonstrated good accuracy in early detection in symptomatic patients, but its role in the diagnosis of asymptomatic patients is uncertain. The aim of our study was to assess IgM and IgG prevalence in sera in a large cohort of HCWs previously subjected to Nasopharyngeal swab test (NST) after accurate risk assessment due to positive COVID-19 patient exposure during an observation period of 90 days.
2407 asymptomatic HCWs that had close contact with COVID-19 patients in the period between April 8th and June 7th were screened with NST based on the RT-PCR method. In parallel, they underwent large-scale chemiluminescence immunoassays involving IgM-IgG serological screening to determine actual viral spread in the same cohort.
During the 90-day observation period, 18 workers (0.75%) resulted positive for SARS-CoV-2 infection at the NST, whereas the positivity rates for IgM and IgG were 11.51% and 2.37%, respectively (277 workers). Despite high specificity, serological tests were inadequate for detecting SARS-CoV-2 infection in patients with previous positive NST results (IgM and IgG sensitivities of 27.78% and 50.00%, respectively).
These findings indicate a widespread low viral load of SARS-CoV-2 among hospital workers. However, serological screening showed very low sensitivity with respect to NST in identifying infected workers, and negative IgG and IgM results should not exclude the diagnosis of COVID-19. IgG-IgM chemiluminescence immunoassays could increase the diagnosis of COVID-19 only in association with NST, and this association is considered helpful for decision-making regarding returning to work.
医护人员（HCWs）由于其特定任务而高度暴露于 SARS-CoV-2 感染。IgG-IgM 血清学检测在有症状患者的早期检测中表现出良好的准确性，但在无症状患者中的诊断作用尚不确定。我们的研究旨在评估在经过 90 天的观察期后，对因接触 COVID-19 阳性患者而有准确风险评估的大量 HCWs 进行鼻咽拭子检测（NST）后，其血清中的 IgM 和 IgG 流行率。
2020 年 4 月 8 日至 6 月 7 日期间，对与 COVID-19 患者有密切接触的 2407 名无症状 HCWs 进行 NST 筛查，方法基于 RT-PCR。同时，他们接受了大规模化学发光免疫分析，包括 IgM-IgG 血清学筛查，以确定同一队列中的实际病毒传播情况。
在 90 天的观察期内，18 名工人（0.75%）的 NST 检测结果呈 SARS-CoV-2 感染阳性，而 IgM 和 IgG 的阳性率分别为 11.51%和 2.37%（277 名工人）。尽管特异性高，但血清学检测不足以检测 NST 结果为阳性的患者的 SARS-CoV-2 感染（IgM 和 IgG 的敏感性分别为 27.78%和 50.00%）。
这些发现表明医院工作人员中 SARS-CoV-2 的病毒载量普遍较低。然而，与 NST 相比，血清学筛查在识别感染工人方面的敏感性非常低，阴性 IgG 和 IgM 结果不应排除 COVID-19 的诊断。仅在与 NST 相关联的情况下，IgG-IgM 化学发光免疫分析才可增加 COVID-19 的诊断，并且这种关联被认为有助于做出重返工作岗位的决策。
