RESUMEN
After the world faced the epidemic of COVID-19 caused by the novel coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), novel clinical evidence and genetics related to this virus are emerging. This virus presents a broad range of clinical manifestations that mainly include various asymptomatic infections and severe pneumonia that are followed by multiple organ failures which could lead to death. The immune system has a critical role in the protection of the body against viruses and diseases and the production of antibodies against pathogens. The present study aimed to investigate the effect of COVID-19 on immune responses of the body. A comprehensive collection of related clinical trials and reviews on the issue of COVID-19 were searched. The main focus of the reviewed studies was on immune response in COVID-19. In this regard, various databases of PubMed, EMBASE, Scopus, CINAHL Plus, Cochrane Library, and Google Scholar were reviewed and all related articles from 2010 to 2021 were investigated. All records were searched in the English language and finally records with the highest thematic relevance were included in the main criteria of the study. It is well-known that the immune system's response to the SARS-CoV-2 virus involves all the components of the immune system that are responsible for viral elimination and recovery of the body. However, these immune system responses are involved in the progression of COVID-19 to a severe and lethal process. When the period of COVID-19 in the body increases, the regulation between protective and altered responses will be lost because of exacerbation of the inflammatory components. Therefore, all the responsible factors which affect immunity should be investigated just like that performed in this study.