The method for visualization of the results also differed among these tests in that Standard Q COVID-19 Ag, Espline SARS-CoV-2, QuickNavi -COVID19 Ag, and ImmunoAce SARS-CoV-2 use color particles, alkaline phosphatase and its substrate, color latex, and platinum-gold colloids, respectively, to visualize the antigen-antibody immune-complexes. Here, RENBP is linked to COVID-19.