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.
Keywords: COVID-19; Healthcare workers; Serological screening.
【저자키워드】 COVID-19, Healthcare workers, Serological screening, 【초록키워드】 serological test, SARS-CoV-2, Healthcare workers, SARS-COV-2 infection, hospital, Diagnosis, risk, RT-PCR, viral spread, healthcare worker, Risk assessment, Prevalence, Nasopharyngeal swab, sensitivity, specificity, Cohort, Viral, Symptomatic patients, Serological tests, Serological assay, Asymptomatic, Accuracy, Viral load, HCWs, chemiluminescence immunoassay, sera, Early detection, Patient, large cohort, Swab test, Decision-making, serological, asymptomatic patients, asymptomatic patient, COVID-19 patients, association, close contact, IgG and IgM, IgM and IgG, HCW, contact with, observation period, positive, positive COVID-19, nasopharyngeal swab test, widespread, screened, determine, demonstrated, diagnosis of COVID-19, with COVID-19, 【제목키워드】 public health, SARS-CoV-2, healthcare worker, Nasopharyngeal swab, serological, IgM and IgG, infection prevalence, Italian,