Cell-mediated and humoral immune response to SARS-CoV-2 vaccination and booster dose in immunosuppressed patients

Importance: Data on the humoral and cellular immune response to primary and booster SARS-CoV-2 vaccination in immunosuppressed patients is limited. Objective: To determine humoral and cellular response to primary and booster vaccination in immunosuppressed patients and identify variables associated with poor response. Design: Retrospective observational cohort study. Setting: Large healthcare system in Northern California. Participants: This study included patients fully vaccinated against SARS-CoV-2 (mRNA-1273, BNT162b2, or Ad26.COV2.S) who underwent clinical testing for anti-SARS-SoV-2 S1 IgG ELISA (anti-S1 IgG) and SARS-CoV-2 interferon gamma release assay (IGRA) from January 1, 2021 through November 15, 2021. A cohort of 18 immunocompetent volunteer healthcare workers were included as reference. No participants had a prior diagnosis of SARS-CoV-2 infection. Exposure(s): Immunosuppressive diseases and therapies. Main Outcome(s) and Measure(s): Humoral and cellular SARS-CoV-2 vaccine response as measured by anti-S1 IgG and SARS-CoV-2 IGRA, respectively, after primary and booster vaccination. Results: 496 patients (54% female; median age 50 years) were included in this study. Among immunosuppressed patients after primary vaccination, 62% (261/419) had positive anti-S1 IgG and 71% (277/389) had positive IGRA. After booster, 69% (81/118) had positive anti-S1 IgG and 73% (91/124) had positive IGRA. Immunosuppressive factors associated with low rates of humoral response after primary vaccination included anti-CD20 monoclonal antibodies (n=48, P<.001), sphingosine 1-phsophate (S1P) receptor modulators (n=11, P<.001), mycophenolate (n=78, P=.002), and B cell lymphoma (n=55, P=.004); those associated with low rates of cellular response included S1P receptor modulators (n=11, P<.001) and mycophenolate (n=69, P<.001). Of patients who responded poorly to primary vaccination, 16% (4/25) with hematologic malignancy or primary immunodeficiency developed a significantly increased humoral response after the booster dose, while 52% (14/27) with solid malignancy, solid organ transplantation, or autoimmune disease developed an increased response (P=.009). Only 5% (2/42) of immunosuppressed patients developed a significantly increased cellular response following the booster dose. Conclusions and Relevance: Cellular vaccine response rates were higher than humoral response rates in immunosuppressed individuals after primary vaccination, particularly among those undergoing B cell targeting therapies. However, humoral response can be increased with booster vaccination, even in patients on B cell targeting therapies.