The interplay between the immune system and SARS-CoV-2 in COVID-19 patients

Millions of people across the globe have been affected by coronavirus disease 2019 (COVID-19), which began in Wuhan, China, and is caused by SARS-CoV-2. COVID-19 has a variety of clinical characteristics and triggers immune responses required for the elimination of the viral agent. Currently, no effective treatment options are available for targeting SARS-CoV-2 infection. Repurposing of drugs such as chloroquine, thalidomide, and leflunomide alongside convalescent plasma is being employed as a therapeutic strategy. Clinical studies have shown that both asymptomatic and symptomatic patients can have an extremely active immune response that is largely attributable to immune system modulations. This includes cytokine storm syndrome (CSS), which affects the adaptive immune system, leading to exhaustion of natural killer (NK) cells and thrombocytopenia in some cases. This review examines the interaction of SARS-CoV-2 with the host immune system and the potential for the development of appropriate immunotherapy for the treatment of COVID-19.