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Large-scale IgM and IgG SARS-CoV-2 serological screening among healthcare workers with a low infection prevalence based on nasopharyngeal swab tests in an Italian university hospital: Perspectives for public health.
Vimercati, Luigi; Stefanizzi, Pasquale; De Maria, Luigi; Caputi, Antonio; Cavone, Domenica; Quarato, Marco; Gesualdo, Loreto; Lopalco, Pier Luigi; Migliore, Giovanni; Sponselli, Stefania; Graziano, Giusi; Larocca, Angela Maria Vittoria; Tafuri, Silvio.
  • Vimercati L; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy. Electronic address: luigi.vimercati@uniba.it.
  • Stefanizzi P; Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy.
  • De Maria L; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
  • Caputi A; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
  • Cavone D; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
  • Quarato M; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
  • Gesualdo L; President, School of Medicine, University of Bari, Bari, Italy.
  • Lopalco PL; Department of Translational Research and of New Surgical and Medical Technologies, University of Pisa, Pisa, Italy.
  • Migliore G; Hospital Director, University Hospital of Bari, Bari, Italy.
  • Sponselli S; Interdisciplinary Department of Medicine, University of Bari, Bari, Italy; Occupational Medicine Unit, University Hospital of Bari, Bari, Italy.
  • Graziano G; Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy.
  • Larocca AMV; Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy.
  • Tafuri S; Department of Biomedical Science and Human Oncology, University of Bari, Bari, Italy.
Environ Res ; 195: 110793, 2021 04.
Article in English | MEDLINE | ID: covidwho-1051629
ABSTRACT

BACKGROUND:

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.

METHODS:

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.

RESULTS:

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).

CONCLUSIONS:

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.
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Full text: Available Collection: International databases Database: MEDLINE Document Type: Article Main subject: SARS-CoV-2 / COVID-19 Subject: SARS-CoV-2 / COVID-19 Type of study: Diagnostic study / Prevalence study / Prognostic study / Risk factors / Screening study Language: English Journal: Environ Res Clinical aspect: Diagnosis / Etiology Year: 2021

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Full text: Available Collection: International databases Database: MEDLINE Document Type: Article Main subject: SARS-CoV-2 / COVID-19 Subject: SARS-CoV-2 / COVID-19 Type of study: Diagnostic study / Prevalence study / Prognostic study / Risk factors / Screening study Language: English Journal: Environ Res Clinical aspect: Diagnosis / Etiology Year: 2021
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