Immunogenicity of quadrivalent meningococcal conjugate vaccine in frequent platelets donors.

Frequent plateletpheresis is associated with severe lymphopenia of uncertain clinical significance. We assessed the functional impact of frequent platelet donations and associated lymphopenia on the response to neoantigens. We conducted a prospective study of 102 meningococcal vaccine naïve (HIV uninfected) platelet donors recruited at Brigham and Women's Hospital. One dose of quadrivalent meningococcal conjugate vaccine was administered. Seroresponse was defined as a fourfold increase of serum bactericidal antibody titers (SBA) and seroprotection was defined as post-vaccination titers ≥1:8, for each of the four vaccine antigens (A, C, W, and Y). Mean age was 61 years old, 69% were male, and medial number of platelet donations in prior year was 14 (IQR 4-20). Frequent platelet donors had a low CD4 count (14% ≤200/µL and 34% ≤350/uL). Seroresponse rates varied from 68% for serogroup Y to 86% for serogroup A and were higher for participants with baseline titers of less than 1:8. Post-vaccination seroprotection rates varied from 76% for serogroup Y to 96% for serogroup A. After adjustments for age, sex, and frequent donations, lower total lymphocyte or lower CD4 counts were not associated with lower responses. These data suggest no impairment by plateletpheresis-associated lymphopenia on response to these neoantigens. This trial was registered at www.clinicaltrials.gov as #NCT04224311.