Detection of SARS-CoV-2 antibodies is insufficient for the diagnosis of active or cured COVID-19

Abstract

We assessed the performance of Abbott's SARS-CoV-2 IgG assay and the Panbio^TM COVID-19 IgG/IgM rapid test device for the diagnosis of either active or cured COVID-19. Three cohorts of patients were chosen. Cohort 1, patients (n = 65) who attended the emergency department on March 30, 2020 with clinical suspicion of active COVID-19 (n = 56 with proven/probable COVID-19). Cohort 2, hospital workers (n = 92) who had either been (n = 40) or not (n = 52) diagnosed with proven/probable COVID-19 and were asymptomatic at the time of the sampling. Cohort 3, patients (n = 38) cared at the hospital before the start of the COVID-19 pandemic. Detection of serum antibodies was done using Abbott´s SARS-CoV-2 IgG assay and the Panbio^TM COVID-19 IgG/IgM device. Both methods showed 98% agreement for IgG detection. No antibodies were detected in the 38 samples from hospitalized pre-COVID subjects. The diagnostic performance of IgGs detected by Abbott´s SARS-CoV-2 assay in Cohorts 1/2 was: sensitivity (60.7%/75%) and specificity (100%/84.6%). The diagnostic performance of IgM by Panbio^TM COVID-19 in Cohorts 1/2 was: sensitivity (16%/17.5%) and specificity (100%/98.1%). We show that IgG detection alone is insufficient for the diagnosis of active or cured COVID-19. IgM detection has a limited diagnostic value.

Figure 1

Scatter plots of index values obtained by Abbott´s SARS-CoV-2 IgG assay (Architect analyser) versus days from the onset of symptoms of all patients (a), and patients from Cohort 1 (b) and Cohort 2 (c). Dots in red indicate proven COVID-19 cases and dots in blue indicate probable COVID-19 cases.