Abstract
Background: Serological tests are a powerful tool in the monitoring of infectious diseases and the detection of host immunity. However, manufacturers often provide diagnostic accuracy data generated through biased studies, and the performance in clinical practice is essentially unclear.
Objectives: We aimed to determine the diagnostic accuracy of various serological testing strategies for (a) identification of patients with previous coronavirus disease-2019 (COVID-19) and (b) prediction of neutralizing antibodies against SARS-CoV-2 in real-life clinical settings.
Methods: We prospectively included 2573 consecutive health-care workers and 1085 inpatients with suspected or possible previous COVID-19 at a Swiss University Hospital. Various serological immunoassays based on different analytical techniques (enzyme-linked immunosorbent assays, ELISA; chemiluminescence immunoassay, CLIA; electrochemiluminescence immunoassay, ECLIA; and lateral flow immunoassay, LFI), epitopes of SARS-CoV-2 (nucleocapsid, N; receptor-binding domain, RBD; extended RBD, RBD+; S1 or S2 domain of the spike [S] protein, S1/S2), and antibody subtypes (IgG, pan-Ig) were conducted. A positive real-time PCR test from a nasopharyngeal swab was defined as previous COVID-19. Neutralization assays with live SARS-CoV-2 were performed in a subgroup of patients to assess neutralization activity (n = 201).
Results: The sensitivity to detect patients with previous COVID-19 was ≥85% in anti-N ECLIA (86.8%) and anti-S1 ELISA (86.2%). Sensitivity was 84.7% in anti-S1/S2 CLIA, 84.0% in anti-RBD+LFI, 81.0% in anti-N CLIA, 79.2% in anti-RBD ELISA, and 65.6% in anti-N ELISA. The specificity was 98.4% in anti-N ECLIA, 98.3% in anti-N CLIA, 98.2% in anti-S1 ELISA, 97.7% in anti-N ELISA, 97.6% in anti-S1/S2 CLIA, 97.2% in anti-RBD ELISA, and 96.1% in anti-RBD+LFI. The sensitivity to detect neutralizing antibodies was ≥85% in anti-S1 ELISA (92.7%), anti-N ECLIA (91.7%), anti-S1/S2 CLIA (90.3%), anti-RBD+LFI (87.9%), and anti-RBD ELISA (85.8%). Sensitivity was 84.1% in anti-N CLIA and 66.2% in anti-N ELISA. The specificity was ≥97% in anti-N CLIA (100%), anti-S1/S2 CLIA (97.7%), and anti-RBD+LFI (97.9%). Specificity was 95.9% in anti-RBD ELISA, 93.0% in anti-N ECLIA, 92% in anti-S1 ELISA, and 65.3% in anti-N ELISA. Diagnostic accuracy measures were consistent among subgroups.
Conclusions: The diagnostic accuracy of serological tests for SARS-CoV-2 antibodies varied remarkably in clinical practice, and the sensitivity to identify patients with previous COVID-19 deviated substantially from the manufacturer’s specifications. The data presented here should be considered when using such tests to estimate the infection burden within a specific population and determine the likelihood of protection against re-infection.
Keywords: COVID-19 diagnostic testing [Supplementary Concept]; Infections/*epidemiology/transmission*Disease Outbreaks; SARS-CoV-2 [Supplementary Concept]; severe acute respiratory syndrome coronavirus 2 [Supplementary Concept]; spike protein.
【저자키워드】 spike protein., COVID-19 diagnostic testing [Supplementary Concept], Infections/*epidemiology/transmission*Disease Outbreaks, SARS-CoV-2 [Supplementary Concept], severe acute respiratory syndrome coronavirus 2 [Supplementary Concept], 【초록키워드】 COVID-19, coronavirus disease, neutralizing antibody, serological test, CLIA, SARS-CoV-2, IgG, coronavirus, Infectious diseases, Neutralizing antibodies, antibody, Infection, diagnostic, Infectious disease, severe acute respiratory syndrome Coronavirus, ELISA, Spike protein, Nasopharyngeal swab, Protein, immunoassay, lateral flow immunoassay, sensitivity, specificity, Epitopes, Diagnostic accuracy, SARS-CoV-2 antibodies, Receptor-binding domain, Serological tests, SARS-CoV-2 antibody, Serological testing, Accuracy, Real-time PCR, nucleocapsid, RBD, enzyme-linked immunosorbent assays, chemiluminescence immunoassay, Patient, analytical techniques, Re-infection, diagnostic testing, respiratory, PCR test, epitope, university, serological, Clinical practice, Anti-S1, anti-RBD, Inpatient, acute respiratory syndrome, acute respiratory syndrome coronavirus, acute respiratory syndrome coronavirus 2, enzyme, host immunity, subgroups, domain, S1/S2, clinical settings, measure, live SARS-CoV-2, neutralization activity, powerful tool, positive, electrochemiluminescence immunoassay, neutralization assays, subtype, S2 domain, likelihood, anti-RBD ELISA, health-care, defined, identify, performed, detect, conducted, determine, subgroup of patient, 【제목키워드】 diagnostic, SARS-CoV-2 antibody, Accuracy,