Abstract
OBJECTIVES: This study aimed to assess the immune response to a three-dose primary series of COVID-19 vaccination in kidney transplant recipients (KTRs), a population vulnerable to infection due to immunosuppression. METHODS: This study was a longitudinal evaluation of neutralizing antibody (nAB) dynamics in 43 KTRs in a lower-middle-income setting receiving a three-dose homologous (messenger RNA [mRNA]-1273-mRNA-1273- BNT162b2) vaccination against COVID-19. Samples were obtained at time points (TP) as follows: TP0, pre-vaccination; TP1, 1-month post-first dose (mRNA-1273); TP2, 1-month post-second dose (mRNA-1273); TP3, 4 months post-second dose; TP4, 2 weeks post-third dose (BNT162b2); TP5, 5 months post-third dose; and TP6, 12 months post-third dose. Anti-SARS-CoV-2 nAB were detected using the Genscript cPass(TM) pseudoviral neutralization kit. Demographic and clinical details were obtained through interviewer-administered questionnaires. RESULTS: Pre-vaccination serum analysis showed n = 7 KTRs had prior COVID-19 infection, classified as 'infected + vaccinated,' while others were 'vaccinated.' Both groups were similar in age (41.7 years vs 46.7 years, P = 0.2383), gender, and transplant characteristics. Seroconversion and mean/ median antibody level (MAB) in the vaccinated and infected + vaccinated KTRs were: TP1, 8.3% vs 100% (P <0.001), MAB = 64.3 IU/mL vs 1424 IU/mL (P = 0.0167); TP2, 52.7% vs 100% (P = 0.0194), MAB = 175 IU/mL vs 2790 IU/mL (P <0.0001); TP3, 100% vs 100%, MAB = 106IU/mL vs 2153 IU/mL (P = 0.0002); TP4, 100% vs 100%, MAB = 736 IU/mL vs 2152 IU/mL (P = 0.0307); and TP6, 100% vs 100%, MAB > 2565 IU/mL vs > 3028 IU/mL (P = 0.5238). No factors were associated with seroconversion or MAB. CONCLUSIONS: KTRs receiving a three-dose mRNA COVID-19 vaccine regimen maintained strong nAB levels at 1-year follow-up, with comparable antibody levels seen between KTRs with prior infection + vaccination and vaccination alone.