Figure 4.

Pathology of lungs in SARS-CoV-2 infection. Early studies on COVID-19 patients biopsies revealed the presence of pulmonary involvement. SARS-CoV-2 infects and use the lung epithelial cells for its propagation. Innate immune system that received the signals from the infection acts as a primary response, such as recruitment of monocytes, macrophages, neutrophils, lymphocytes, and others. Due to the enormous increase in the virions that hijack the immune system response; consequently, hyper activated immune system produces copious amounts of cytokines (i.e., cytokine storm), which damages the host cells. The cumulative effect, caused by the virus and the immune system, leads to the damage of alveoli followed by reduced gas transportation. SARS-CoV-2, Severe acute respiratory syndrome coronavirus 2.