Performance of Severe Acute Respiratory Syndrome Coronavirus 2 Antibody Assays in Different Stages of Infection: Comparison of Commercial Enzyme-Linked Immunosorbent Assays and Rapid Tests

Abstract

We comparatively assessed sensitivities and specificities of 4 commercial enzyme-linked immunosorbent assays (ELISAs) and 2 rapid tests in 77 patients with polymerase chain reaction-confirmed severe acute respiratory syndrome coronavirus 2 infection, grouped by interval since symptom onset. Although test sensitivities were low (<40%) within the first 5 days after disease onset, immunoglobulin (Ig) M, IgA, and total antibody ELISAs increased in sensitivity to >80% between days 6 and 10 after symptom onset. The evaluated tests (including IgG and rapid tests) provided positive results in all patients at or after the 11th day after onset of disease. The specificities of the ELISAs were 83% (IgA), 98% (IgG), and 97% (IgM and total antibody).

Keywords: SARS; antibodies; coronavirus; immunoassay.

Figure 1.

A, Comparison of individual antibody levels and sensitivities of enzyme-linked immunosorbent assays among 77 patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, subgrouped by the interval since onset of symptoms. B, Sensitivities of the Wantai SARS-CoV-2 Ab Rapid Test and the 2019-nCoV IgG/IgM Rapid Test (immunoglobulin [Ig] M and IgG bands; Hangzhou AllTest Biotech) in 77 patients with SARS-CoV-2 infection, grouped by interval since onset of symptoms. Abbreviations: Pos/Neg or Brdl, positive/negative or borderline results.

Figure 2.

Specificities of the Euroimmun severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) immunoglobulin (Ig) A and IgG and the Wantai IgM and total antibody enzyme-linked immunosorbent assays (A) as well as the Wantai SARS-CoV-2 Ab and the 2019-nCoV IgG/IgM Rapid Test (IgM and IgG bands; Hangzhou AllTest Biotech) (B), as assessed in 100 non–SARS-CoV-2–infected controls.