The model explicitly describes dynamics of five crucial functional quantities that determine COVID-19 progression: virus (V) and interleukin 6 (IL-6, I) for pathogenic function, effector T cells (Te) and neutralizing antibodies (NAbs, A) for protective function, D-dimer (coagulation marker, Sd) and high-sensitivity cardiac troponin I (HSCT, heart injury marker, Sh) as examples for multiorgan damage. The gene discussed is IL6; the disease is COVID-19.