Common variable immunodeficiency (CVID) is characterized by
hypogammaglobulinemia and/or a defective antibody response to T-dependent and
T-independent antigens. CVID response to immunization depends on the
antigen type, the
vaccine mechanism, and the specific patient immune defect. In CVID patients, humoral and cellular responses to the currently used
COVID-19 vaccines remain unexplored. Eighteen CVID subjects receiving 2-dose anti-SARS-CoV-2
vaccines were prospectively studied. S1-antibodies and S1-specific IFN-γ T cell response were determined by ELISA and FluoroSpot, respectively. The immune response was measured before the administration and after each dose of the
vaccine, and it was compared to the response of 50 healthy controls (HC). The development of humoral and cellular responses was slower in CVID patients compared with HC. After completing vaccination, 83% of CVID patients had S1-specific
antibodies and 83% had S1-specific T cells compared with 100% and 98% of HC (p = 0.014 and p = 0.062, respectively), but
neutralizing antibodies were detected only in 50% of the patients. The strength of both humoral and cellular responses was significantly lower in CVID compared with HC, after the first and second doses of the
vaccine. Absent or discordant humoral and cellular responses were associated with previous history of autoimmunity and/or lymphoproliferation. Among the three patients lacking humoral response, two had received recent
therapy with anti-B cell
antibodies. Further studies are needed to understand if the response to
COVID-19 vaccination in CVID patients is protective enough. The 2-dose
vaccine schedule and possibly a third dose might be especially necessary to achieve full immune response in these patients.