CHMP5 and COVID-19: To optimize the number of cells in the SARS-CoV-2-D614Gdel21-GFP titration and neutralization test, a triad of representative positive samples, namely monoclonal antibody AM180 (Sample 1); convalescent COVID-19 patient serum (Sample 2); and guinea pig D614G spike protein of SARS-CoV-2 immunized three times serum (Sample 3) were employed.