IFNG and systemic inflammatory response syndrome: Considering that NK cells are among the main producers of IFN-γ, they are possibly among the leading culprits behind the cytokine storm led by IFN-γ that triggers inflammation-mediated acute lung injury, acute respiratory distress syndrome (ARDS), systemic inflammatory response syndrome (SIRS)/sepsis and subsequent morbidity and mortality associated with COVID-19 [69, 70].