In summary, despite significant underlying T lymphopenia and absence of B cells, this patient with hypomorphic SCID experienced mild COVID-19 disease that resolved without pharmacologic therapy. Interestingly, a series of patients with common variable immunodeficiency (CVID), in which B cells are dysfunctional but not absent, experienced a more severe clinical course, suggesting a role for dysregulated B cell responses in COVID-19 immunopathology [[12]]. To the Editor, The viral etiology of coronavirus disease 2019 (COVID-19), caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), led to initial conjecture that T cell and B cell responses would be essential for disease resolution [[1]]. While disproportionately high rates of lethality have been documented in SCID patients in an analysis of IEI patients with COVID-19, successful clinical outcomes have been observed in select cases [[3], [10]]. [Extracted from the article]