Atellica im sars cov 2 igg

Four antibody binding assays were used for serological testing according to the instructions of the manufacturer. Two were quantitative: Abbott SARS-CoV-2 IgG II Quant-test (Abbott) (Abbott France, Rungis, France) with 50 arbitrary units (AU)/ml as a threshold for positivity, and Roche Elecsys anti-SARS-CoV-2 S (Roche Diagnostics France, Meylan, France) with 0.8 AU/ml used as a threshold for positivity. Two were semi-quantitative: Beckman Access SARS-CoV-2 IgG II (Beckman Coulter France SAS, Roissy CDG, France) with 30 AU/ml as a threshold for positivity and Siemens Atellica® IM SARS-CoV-2 IgG (Siemens Healthcare SAS, Saint-Denis, France) with 0.8 AU/ml used as a threshold for positivity.
BAU/ml proposed by the WHO, to standardize any assay to the WHO International Standard, were calculated by applying the following conversion factors as suggested by the manufacturers: Abbott, BAU/ml = (1/7) × Antibody Units (AU)/ml, Beckman, BAU/ml = 1 × AU/ml, Roche, BAU/ml = 1.029 × AU/ml, and Siemens, BAU/ml = 21.8 × AU/ml.
The neutralizing capacity was estimated by performing a surrogate virus neutralization test (sVNT) assay (GenScript, Piscataway, NJ, USA) as previously described [10 (link),15 (link),16 (link)]. This assay detects antibodies that block the interaction of SARS-CoV-2 with its entry receptor angiotensin-converting enzyme 2. A threshold of 20% was used for positivity.

The humoral response to the third dose was measured two weeks after the vaccine administration with the Siemens Healthineers Atellica® IM SARS-CoV-2 IgG (sCOVG) assay, which detects anti-S1-RBD IgG. The assay is considered non-reactive when the result is less than 1 or reactive when greater than or equal to 1, with a maximum measurable range of up to 150 U/mL limiting the antibody response intensity analysis and constituting a potential source of bias. According to the manufacturer, this test has a 96.41% sensitivity (95% CI 92.74–98.54%) and 99.9% specificity (95% CI: 99.63–99.99%).