Twenty-four (92.3%) of the 26 SARS-CoV-2 infected patients were reactive in one or both versions of the IgG recomLine assay; the test results differed only in three sera (Figure 1). One out of the ten archived sera that were reactive in at least one of the SARS-CoV-2 IgG/total antibody tests was also classified as SARS-CoV-2 IgG-positive by the prototype immunoblot (v1) but was negative in the improved version 2. The underlying sample #7 was collected in the winter 2018/2019 and was found to be reactive for SARS-CoV-2 IgG/total antibodies by the Mikrogen (S/CO 1.33), Roche (S/CO 3.46), and Viramed (N antigen 125 ViraChip® Units) assays in parallel (Figure 2). The twelve routine samples were analyzed by both versions of the blot (v1: nine samples and v2: all samples), and results of the immunoassays were largely confirmed (Figure 3).