BACKGROUND: The lower humoral immunity response after the COVID-19 vaccine in kidney transplant recipients (KTR) has been reported in several studies. However, there are few studies on the efficacy of the ChAdOx1 nCoV-19 (AstraZeneca) vaccine compared between various immunosuppressive regimens. METHODS: We conducted a prospective cohort study at Siriraj Hospital, Bangkok, Thailand. Adult KTRs who received two doses of the ChAdOx1 nCoV-19 vaccine at intervals of 3 months were enrolled. Anti-SARS-COV-2 S-RBD-IgG antibody (anti-RBD) was assessed at the one month after the second dose and considered positive if the level ≥50 AU/mL or 7 BAU/mL. The primary outcome was the seropositivity of anti-RBD. The association between type, dose, and level of immunosuppressive regimen and anti-RBD seropositivity was analyzed. RESULTS: Between October 2021 and January 2022, 139 KTRs with a median time of 55 months (IQR, 29-102 months), were enrolled. The mean age was 49.1 ± 11.3 years and 64.7 % were men. Seroconversion of anti-RBD was found in 72 patients (51.8 %). The seropositive rate was significantly higher in KTR who received tacrolimus (TAC)/everolimus (EVR)/prednisolone (CS) immunosuppression than EVR/mycophenolic acid (MPA)/CS and TAC/MPA/CS, respectively (95 % vs. 65 % vs. 34 %
CONCLUSION: The anti-RBD response after ChAdOx1 nCoV-19 vaccination was revealed in 51.8 % of the KTR. KTRs who received the TAC/EVR/CS regimen had the highest immune response after vaccination, relatively comparable to the general population. The immunosuppressive regimen should be considered for a further vaccine dose in KTR.