Longitudinal evaluation of anti-SARS-CoV-2 neutralizing antibody levels in 3-dose homologous (mRNA-1273- mRNA-1273- BNT162b2) vaccinated Kidney transplant population: 18-month follow-up.

BackgroundKidney transplant recipients (KTRs) were given a 3-dose primary series of COVID-19 vaccination as they were vulnerable to infection due to immunosuppression. MethodsThis study was a longitudinal evaluation of nAB dynamics in 43 KTRs in a low-middle income setting receiving 3-dose homologous (mRNA-1273- mRNA-1273- BNT162b2) vaccination against COVID-19. Samples were obtained at time-points (TP) 0- 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 Genscript cPassTM pseudoviral neutralization kit. Demographic and clinical details were obtained through interviewer administered questionnaires. ResultsPre-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(41.7years vs 46.7years,p=0.2383), gender, and transplant characteristics. Seroconversion and MAB in the vaccinated and infected+vaccinated KTRs were:TP1-8.3% vs 100%(p<0.001), MAB-64.3IU/ml vs 1424IU/ml(p=0.0167TP2-52.7% vs 100%(p=0.0194), MAB-175IU/ml vs 2790IU/ml(p<0.0001), TP3-100% vs 100%, MAB-106IU/ml vs 2153IU/ml(p=0.0002), TP4-100% vs 100%, MAB-736 IU/ml vs 2152IU/ml(p=0.0307) and TP6-100% vs 100%, MAB >2565IU/ml vs >3028IU/ml(p=0.5238) No factors were associated with seroconversion or MAB. ConclusionKTRs receiving a three-dose mRNA COVID-19 vaccine regime maintained strong nAB levels at one-year follow-up, with comparable antibody levels seen between KTRs with prior infection + vaccination and vaccination alone.