Focusing on IgG antibodies, we demonstrate the performance of two enzyme‐linked immunosorbent assay (ELISA) assays (Euroimmun SARS‐CoV‐2 IgG and Vircell COVID‐19 ELISA IgG) in comparison to one lateral flow assay (FaStep COVID‐19 IgG/IgM Rapid Test Device) and two in‐house developed assays (immunofluorescence assay [IFA] and plaque reduction neutralization test [PRNT]). This evidence concerns the gene CD40LG and COVID-19.