NFKB1 and COVID-19: Whereas the majority of subjects with primary immunodeficiencies, or inborn errors of immunity (IEI), undergo a mild course of COVID-19, people with some specific forms of IEI, as combined immunodeficiencies, antibody defects (i.e., X-linked agammaglobulinemia) or NF-kB deficiency, showing an impairment of the adaptive immune responses may fail to control SARS-CoV-2 infection and may be at higher risk of developing severe COVID-19 [67,68].