ABSTRACT
BACKGROUND AND AIMS: COVID-19 infection has heavily impacted our national health system since March-2020. Although the kidney transplant (KT) activity was strongly reduced initially, nowadays it is partially recovered by using 'COVID-clean' pathways and vaccination of KT candidates since February-2021. However, scarce information is available regarding how de novo KT immunosuppression influences the serological status of vaccinated recipients. METHOD: We reviewed the course of 38 de novo KT recipients transplanted between March-September 2021 fully vaccinated before KT. SARS-CoV-2 IgG antibodies against Spike (IgG-S) before and after KT (median: 32 days) were quantified with a serological assay (positive ≥13.0 AU/mL). RESULTS: Of 38 recipients, 35 showed positive IgG-S at KT (92%). We exclude from the analysis, 4 recipients with COVID infection which interfered the analysis and 5 with inappropriate samples. The remaining 26 recipients had received the second dose of the mRNA vaccine a median time of 48 days before the pre-KT IgG determination. All patients maintained IgG-S over the cut-off after KT, but we observed that half de novo recipients (53.8%) showed a 50% reduction in the level of IgG-S at 1 month: 12/20 (60%) of those who received induction with basiliximab and 2/6 (33%) who received thymoglobulin. Regarding the impact of maintenance immunosuppression under induction with basiliximab, the IgG-S levels halved in 50% of those with tacrolimus-mycophenolate and 67% with tacrolimus-everolimus. The restricted analysis of IgG-S levels excluding five outliers before KT (>800 AU/mL) showed the most intense reduction in three KT recipients who received thymoglobulin-tacrolimus- mycophenolate (263.8 versus 68.8, 74%) compared with seven basiliximab-tacrolimus-mycophenolate cases (494.4 versus 359.8, 27%) and eleven basiliximab-tacrolimus-everolimus (344.0 versus 306.4, 11%) KT recipients. CONCLUSION: Immunosuppression in de novo KT recipients reduces significantly the seroprotective levels of antibodies anti-Spike induced by COVID m-RNA vaccines in more than half the recipients. In our experience, the combination of thymoglobulin, tacrolimus and mycophenolate produces a more intense reduction than the combination of basiliximab with tacrolimus and mycophenolate or everolimus.