text: SARS CoV 2 Infection in the Immunodeficient Host Necessary and Dispensable Immune Pathways Since its outbreak in late December 2019 in Wuhan coronavirus disease 2019 pandemic has posed a therapeutic challenge for the world population with a plenty of clinical pictures and a broad spectrum of severity of the manifestations In spite of initial speculations on a direct role of primary or acquired immune deficiency in determining a worse disease outcome recent studies have provided evidence that specific immune defects may either serve as an experimentum naturae entailing this risk or may not be relevant enough to impact the host defense against the virus Taken together these observations may help unveil pathogenetic mechanisms of the infection and suggest new therapeutic strategies Thus in this review we summarize current knowledge regarding the mechanisms of immune response against severe acute respiratory syndrome coronavirus 2 infection and clinical manifestations with a special focus on children and patients presenting with congenital or acquired immune deficiency 