Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a viral agent that causes Coronavirus disease 2019 (COVID-19), a disease that causes flu-like symptoms that, when exacerbated, can have life-threatening consequences. COVID-19 has been linked to persistent symptoms, sequelae, and medical complications that can last months after the initial infection. This systematic review aims to elucidate the innate and adaptive immune mechanisms involved and identify potential characteristics of COVID-19 pathology that may increase symptom duration. We also describe he three different stages of COVID-19-viral replication, immune hyperactivation, and post-acute sequelae-as well as each phase's corresponding immune response. Finally, we use this multiphasic approach to describe different treatment approaches for each of the three stages-antivirals, immunosuppressants and monoclonal antibodies, and continued immunosuppressants-to fully curate the treatment to the stage of disease.
Keywords: COVID-19; IL-6; SARS-CoV-2; cytokine storm; immune response; immunotherapy; monoclonal antibody; multi-phasic; natural killer cell; treatment.