Comparison of humoral response in kidney transplant recipients and donors and healthy volunteers following second dose of SARS-CoV-2 mRNA vaccine
This prospective observational study investigated the kinetics and durability of the anti-spike glycoprotein (S) immunoglobulin G (IgG) following the 2nd dose of mRNA-based severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccine in kidney transplant recipients, as compared to those in chronic kidney disease (CKD) and healthy controls. We further identified factors negatively associated with SARS-CoV-2 vaccine effectiveness in kidney transplant recipients. We enrolled 378 kidney recipients (Recipients) who had no history of coronavirus disease 2019 (COVID-19), had no anti-S-IgG before the first vaccine, and had received a 2nd mRNA-based vaccine dose. Antibodies were detected using an immunoassay more than 4 weeks after the 2nd vaccine dose. Anti-S-IgG < 0.8 U/mL, ≥ 0.8 U/mL up to 15 U/mL, and > 15 U/mL were defined as negative, weak positive, and strong positive, respectively, while anti-N-IgG was negative. Anti-S-IgG was also determined in 990 healthy volunteers (HV) and in 102 kidney donors (Donor). The anti-S-IgG (U/mL) titer was 154, 2475, and 1181 in the Recipient, HV, and Donor groups, respectively, with values significantly lower in Recipients. In the Recipient group, the anti-S-IgG-positivity rate gradually increased with the detecting time following the 2nd vaccination, suggesting that Recipients had a delayed response, compared to a 100% positivity rate at an earlier time point in the HV and Donor groups. The anti-S-IgG titer decreased linearly in the Donor and HV groups, whereas it remained stable in Recipients, although at a significantly lower level. Furthermore, by multivariate analysis, independent negative factors associated with the anti-S-IgG titer in Recipients were age > 60 years, duration after kidney transplant < 10 years, and lymphocytopenia. Thus, kidney transplant recipients demonstrate delayed and attenuated responses with lower SARS-CoV-2 antibody titers after the 2nd dose of mRNA-based COVID-19 vaccine.