Enzyme-Linked Immunosorbent Assay for the Detection of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) IgM/IgA and IgG Antibodies Among Healthcare Workers

Abstract

Background The outbreak of the novel coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been spreading rapidly across the world. A nucleic acid real-time quantitative polymerase chain reaction (RQ-PCR) test of nasopharyngeal samples is the standard method for the diagnosis of an active SARS-CoV-2 infection. However, many limitations of the RQ-PCR tests make them unsuitable for the simple and rapid diagnosis of COVID-19 patients. Moreover, some individuals with COVID-19 present an asymptomatic infection. Thus, assessing the asymptomatic transmission of COVID-19, especially in healthcare workers (HCWs), is crucial for evaluating the efficiency of the current preventive measures. Serological tests such as enzyme-linked immunosorbent assay (ELISA) are needed to quickly identify a large number of asymptomatic carriers to prevent the further spread of the virus and assess level of possible serological immunity in a community. Method Between April 18 and June 17, 2020, 330 HCWs from five Madinah region-affiliated hospitals underwent a seroprevalence screening for anti-SARS-CoV-2 antibodies (immunoglobulin [Ig]M/IgA and IgG) using indirect ELISA testing. Result Among the 330 samples, 80 (24.24%) were positive for SARS-CoV-2 IgM/IgA and/or IgG antibodies. There were no significant differences observed in the seroprevalence among the different occupations of the HCWs (excluding the pharmacists) with respect to the percentage of their seropositive samples. Conclusion The current study presented the seroprevalence of anti-SARS-CoV-2 IgM/IgA and IgG antibodies in HCWs. The regular screening of HCWs for these antibodies is necessary; subsequently, a molecular test is recommended for those with seropositive (IgM, IgA, and IgG) samples to assess their viral load and potential shedding.

Keywords: anti-sars-cov-2; covid-19; elisa; hcws; sars-cov-2; seroprevalence.

Figure 1. (A) Serological levels of positive severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific IgM/IgA antibodies in samples from health care workers (HCWs), (B) Serological levels of positive SARS-CoV-2-specific IgG antibodies in samples from HCWs. The lanes mark of the seropositivity threshold. S/CO, signal-to-cutoff.