CXCR5 and common variable immunodeficiency: Further studies are needed to confirm that CXCR5-negative peripheral helper T cells induce B cell responses in CVID patients following COVID-19 vaccination, but it is intriguing to note that peripheral T helper cells have been implicated in extrafollicular B cell differentiation (46), and IgG responses in CVID patients vaccinated against COVID-19 have been ascribed to atypical memory B cell responses producing low affinity spike protein-specific antibodies as a result of extrafollicular B cell differentiation (18).