Response to SARS-CoV-2 varies greatly among patients, from no symptoms to mild or severe disease that may end with death. The disease severity differs according to the host immune response and hence treatment plans differ. This review aimed to insight clearly the pathophysiology of the disease and to develop strategies either to enhance the compromised immunity or to modulate the hyperactive immune response in COVID-19. PubMed/MEDLINE, ScienceDirect, Scopus, Research Gate and Google Scholar have been searched and reviewed for the different pathways of COVID-19 pathogenesis. The host immune response against COVID-19 virus ends in one of these three pathways, these are either: (1) With virus clearance that occurs through highly orchestrated dialogue among innate and adaptive immune cells, or (2) Immune hyperactivity that results in cytokine storm through massive production of inflammatory mediators, which makes the cell out of control and ends with acute respiratory distress syndrome or (3) Immune-mediated coagulopathy, which induces disseminated intravascular coagulation which in most patients ultimately ends with death. In conclusion, the state of entanglement between the virus and its host is a struggle that can spin out of immune system control. The precise understanding of the current COVID-19 pathophysiology should direct the treatment strategy in such a way to protect the patient from serious infection complications.
Spectrum of immunopathogenesis in coronavirus disease 2019 (Covid-19): An updated review