3.1. Natural immunity
The SARS-CoV2 like the other member of coronavirus family is habitually reluctant to stimulate innate immune cells such as dendritic cells and hamper the antiviral type I and III interferon responses [8]. So, thwarting the innate immune responses by SARS-CoV-2 leads to the prolongation of incubation period and smooth transmission of the pathogenic agent without clinical symptoms [9]. Besides the eruptive replication of the SARS-CoV2 virions in the early stages of the disease corroborant of the slant innate immunity and considered as a foundation for ensuing cytokine storm complications especially in severe COVID-19 patients [10]. So, the infected patients experienced elevated circulatory levels of inflammatory cytokines and chemokines, enhanced overactivated blood monocytes and neutrophils [11, 12] and M1 macrophages accumulation in the lung which derived from CD14+/CD16+ proinflammatory monocytes [13]. Also, lack of early restriction of SARS-CoV2 replication in the airways by innate immunity leads to viral overload and resultant hyper inflammatory syndromes including acute respiratory distress syndrome (ARDS) [8].