Fig. 4.

COVID-19 disease progression. COVID-19 Infected patients are categorized into groups of severely symptomatic (A), mild symptomatic (B), and asymptomatic (C) based on the clinical manifestations associated with disease progression into different stages. The SARS-CoV-2 infection progresses in several stages including (I) asymptomatic incubation period, (II) moderately symptomatic period, (III) severe respiratory symptomatic stage progressing ARDS. Here disease progress in these categories depicted in graphical curves indicating viral load variations from infection to clearance. Also, the main cellular and molecular mechanisms are addressed for each group.