Four commercial, widely available assays and a scalable 384-well ELISA can be used for SARS-CoV-2 serological testing to achieve sensitivity and specificity of at least 98%. The Siemens assay and Oxford immunoassay achieved these metrics without further optimisation. This benchmark study in immunoassay assessment should enable refinements of testing strategies and the best use of serologicalThe aim of the study was to evaluate the titer of anti-SARS-CoV-2 IgG antibodies against the S1 subunit of the virus’s spike protein as a marker of the humoral response in 477 patients and the concentration of interferon-gamma as an indicator of cellular response in 28 individuals.
Both IgG and neutralising antibodies are correlates of protection against SARS-CoV-2 infection. Our data suggest that IgG concentrations higher than 500 BAU/mL and neutralising antibody titres of 1024 or more are thresholds for immunological protection from SARS-CoV-2 delta variant infection. Potentially, updated protective thresholds against emerging variants of concern could be calculated
SARS-CoV-2 50% neutralizing antibody titer (NT50) concentrations and anti-SARS-CoV-2 receptor-binding domain (RBD) IgG concentrations for the overall convenience sample of 3,067 serum specimens
(A) Human sera containing IgG antibodies to SARS-CoV-2 (green), MERS-CoV (blue), or HCoV-HKU1 (purple) were subjected to the developed COVID-19 NP IgG ELISA. ( B ) Samples obtained for vaccinated people (blue) or recovered patients (green) were tested for the presence of IgG antibodies directed to SARS-CoV-2 S protein (left panel) and NP. 345 294 46 157 380 121 395 14