Six‐months immunogenicity of BNT162b2 mRNA vaccine in heart transplanted and ventricle assist device‐supported patients

AIMS: To assess the 6 months immunogenicity to severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) mRNA vaccine in a population of heart transplanted (HTx) recipients and left ventricular assist device (LVAD)‐supported patients. METHODS AND RESULTS: A prospective single‐centre cohort study of HTx recipients and LVAD‐supported patients who received a two‐dose SARSCoV‐2 mRNA vaccine (BNT162b2, Pfizer‐BioNTech). Whole blood for anti‐spike IgG (S‐IgG) antibodies were drawn at 6 months after the first vaccine dose. S‐IgG data at 6 weeks were available for a subgroup of HTx recipients. S‐IgG ≥ 50 AU/mL were interpreted positive. The cohort included 53 HTx recipients and 18 LVAD‐supported patients. The median time from HTx or LVAD implantation to the 1(st) vaccine dose was 90 (IQR 30, 172) months and 22 (IQR 6, 78) months, respectively. The seropositivity rates of S‐IgG antibodies and their titre levels in HTx recipients and LVAD‐supported patients were 45% and 83% respectively, (P = 0.006), and 35 (IQR 7, 306) AU/mL and 311 (IQR 86, 774) AU/mL, respectively, (P = 0.006). Reduced SARSCoV‐2 vaccine immunogenicity in HTx recipients was associated with older age [odds ratio (OR) 0.917 confidence interval (CI 0.871, 0.966), P = 0.011] and with the use of anti‐metabolites‐based immunosuppressive regimens [OR 0.224 (CI 0.065, 0.777), P = 0.018]. mTOR inhibitors were associated with higher immunogenicity [OR 3.1 (CI 1.01, 9.65), P = 0.048]. Out of 13 HTx recipients who were S‐IgG seropositive at 6 weeks after the first vaccine dose, 85% remained S‐IgG seropositive at 6 month follow‐up. CONCLUSIONS: At 6 months post‐vaccination, S‐IgG immunogenicity in HTx recipients is low, particularly in older HTx recipients and in those treated with anti‐metabolites drugs.