LAUSR

Immunogenicity following inactivated SARS‐CoV‐2 vaccination among solid organ transplant recipients has not been assessed. Seventy‐five patients (37 kidney transplant [KT] recipients and 38 healthy controls) received two doses, at 4‐week intervals, of an inactivated whole‐virus SARS‐CoV‐2 vaccine. SARS‐CoV‐2‐specific humoral (HMI) and cell‐mediated immunity (CMI) were measured before, 4 weeks post‐first dose, and 2 weeks post‐second dose. The median (IQR) age of KT recipients was 50 (42–54) years and 89% were receiving calcineurin inhibitors/mycophenolate/corticosteroid regimens. The median (IQR) time since transplant was 4.5 (2–9.5) years. Among 35 KT patients, the median (IQR) of anti‐RBD IgG level measured by CLIA after vaccination was not different from baseline, but was significantly lower than in controls (2.4 [1.1–3.7] vs. 1742.0 [747.7–3783.0] AU/ml, p < .01) as well as percentages of neutralizing antibody inhibition measured by surrogate viral neutralization test (0 [0–0] vs. 71.2 [56.8–92.2]%, p < .01). However, the median (IQR) of SARS‐CoV‐2 mixed peptides‐specific T cell responses measured by ELISpot was significantly increased compared with baseline (30 [4–120] vs. 12 [0–56] T cells/106 PBMCs, p = .02) and not different from the controls. Our findings revealed weak HMI but comparable CMI responses in fully vaccinated KT recipients receiving inactivated SARS‐CoV‐2 vaccination compared to immunocompetent individuals (Thai Clinical Trials Registry, TCTR20210226002).