The spike glycoprotein of SARS-CoV-2 is a highly conserved surface protein and as such may represent a good target for immunoassay detection. We screened a variety of antibodies that were reactive to the S glycoprotein in a highly sensitive liquid immunoassay format and also on paper-based or lateral flow assay (LFA) to assess their analytical performance. Our findings included significant variation in performance when using different sources of S antigen. We identified several antibody pairs that had an LOD of below 10 pg/mL in the liquid immunoassay format with the lowest being 3 pg/mL. The antibodies were highly specific to SARS-Cov-2 based on cross reactivity screening with other human CoVs. The LFA screening found some different optimal antibody pairs from the pool of candidate antibodies used but a several antibodies were observed to have high performance with either immunoassay format.