Fig. 2.

Different stages involved in the COVID-19 course of infection. Stage 1: Incubation phase. The patient will be having cough, headaches, and fever with the multiplication of virus inside the host over time. Stage 2: Pulmonary phase. In this phase, the patient suffers from hypoxia, pneumonia and the host immune system starts to respond to the infection with the release of antibodies and other metabolites. Stage 3: Convalescence phase. In this phase, the patient suffers from fatal acute respiratory distress syndrome. Reproduced with permission from Ref. [22].