In addition, when the urea dissociation concentration in ELISA was 4 mol/liter and the dissociation time was 10 min, the results for 19 of the 22 with RF-IgM-positive sera that had given false-positive results for SARS-CoV-2 IgM turned negative, whereas the 14 sera from COVID-19 patients were not affected. The gene discussed is CD40LG; the disease is COVID-19.