Performance Characteristics of the Vidas SARS-CoV-2 IgM and IgG Serological Assays

Abstract

The COVID-19 pandemic, caused by the new severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), continues to spread worldwide. Serological testing for SARS-CoV-2-specific antibodies plays an important role in understanding and controlling the pandemics, notably through epidemiological surveillance. Well validated and highly specific SARS-CoV-2 serological assays are urgently needed. We describe here the analytical and clinical performance of VIDAS® SARS-CoV-2 IgM and VIDAS® SARS-CoV-2 IgG, two CE-marked, EUA-authorized, automated, qualitative assays for the detection of SARS-CoV-2-specific IgM and IgG, respectively. Both assays showed high within-run and within-laboratory precision (coefficients of variation < 11.0%) and very low cross-reactivity towards sera of patients with a past common coronavirus or respiratory virus infection. Clinical specificity determined on up to 989 pre-pandemic healthy donors was ≥ 99% with a narrow 95% confidence interval for both IgM and IgG assays. Clinical sensitivity was determined on up to 232 samples from 130 RT-PCR-confirmed SARS-CoV-2 patients. The positive percent agreement (PPA) with SARS-CoV-2 PCR reached 100% at ≥ 16 days (VIDAS® SARS-CoV-2 IgM) and ≥ 32 days (VIDAS® SARS-CoV-2 IgG) of symptom onset. Combined IgM/IgG test results improved the PPA compared to each test alone. SARS-CoV-2 IgG seroconversion followed closely that of SARS-CoV-2 IgM and remained stable over time, while SARS-CoV-2 IgM levels rapidly declined. Interestingly, SARS-CoV-2-specific IgM and IgG responses were significantly higher in COVID-19 hospitalized vs. non-hospitalized patients. Altogether, the VIDAS® SARS-CoV-2 IgM and IgG assays are highly specific and sensitive serological tests suitable for the reliable detection of past acute SARS-CoV-2 infections.

Prospective Cohort Study of the Kinetics of Specific Antibodies to SARS-CoV-2 Infection and to Four SARS-CoV-2 Vaccines Available in Serbia, and Vaccine Effectiveness: A 3-Month Interim Report

“…The specificity and positive percent agreement of the 9COG test have been evaluated to be ≥99% and 100% at ≥16 days of symptoms onset [ 8 ].…”

The association of maternal SARS‐CoV‐2 vaccination‐to‐delivery interval and the levels of maternal and cord blood antibodies

“…When comparing those testing positive for umbilical cord anti‐spike IgG antibodies (level ≥50 AU/ml; n = 51) with those testing negative (level <50 AU/ml; n = 7), a higher median interval was found from first vaccination to delivery in the positive antibodies group (34.0 [24.0–43.0] vs. 12 10 , 11 , 12 , 13 ; P < 0.001) (Table 3 ).…”

“…Levels above 1.4 RLU were considered positive 12 . Anti‐spike IgM antibodies were interpreted as negative when i was less than 1.00 and positive when i was 1.00 or above 13 …”

Seroconversion in septic ICU patients presenting with COVID-19: necessary but not sufficient

“…Immunoglobulin measurements were performed using Vidas® SARS-CoV-2 IgM and Vidas® SARS-CoV-2 IgG (bioMérieux, France) in vitro diagnostic (IVD) assays ( 11 ). Briefly, a solid-phase repository coated with the antigen (recombinant SARS-CoV-2 receptor-binding domain [RBD] of the viral spike [S] protein) served as both solid-phase and pipetting device.…”