Fig. 3.

The cycle of infection and recovery. Infection loop in mild symptomatic infected cases includes events of primary inflammation, cytokine release, and recruitment of immune cells leading to recovery. In severe symptomatic infected cases, the primary inflammation loop also with the occurrence of seroconversion and ADE response develops cytokine storm and secondary inflammatory responses. In this context, secondary inflammation could cause severe damage and subsequent immune dysfunction. These also lead to loss of ACE2 expressing cells and final ACE2 downregulation, which together with the elevation of neutralizing activity of antibodies and soluble ACE2 resulted in viral clearance and recovery.