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/10 6 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).

Vaccination with inactivated SARS-CoV-2 virus produces suboptimal immune responses among kidney transplant (KT), peritoneal dialyzed (PD), and hemodialyzed (HD) patients. Participants were vaccinated with two-dose inactivated SARS-CoV-2 vaccine (V2) and a third dose of ChAdOx1 nCoV-19 vaccine (V3) at 1–2 months after V2. We enrolled 106 participants: 31 KT, 28 PD, and 31 HD patients and 16 controls. Among KT, PD, and HD groups, median (IQR) of anti-receptor binding domain antibody levels were 1.0 (0.4–26.8), 1092.5 (606.9–1927.2), and 1740.9 (1106–3762.3) BAU/mL, and percent neutralization was 0.9 (0–9.9), 98.8 (95.9–99.5), and 99.4 (98.8–99.7), respectively, at two weeks after V3. Both parameters were significantly increased from V2 across all groups (p < 0.05). Seroconversion and neutralization positivity rates in PD, HD, and control groups were 100% but were impaired in KT patients (39% and 16%, respectively). S1-specific T-cell counts were increased in PD and HD groups (p < 0.05) but not in KT patients. The positive S1-specific T-cell responder rate was > 90% in PD, HD, and control groups, which was higher than that in KT recipients (74%, p < 0.05). The heterologous inactivated virus/ChAdOx1 nCoV-19 vaccination strategy elicited greater immunogenicity among dialysis patients; however, inadequate responses remained among KT recipients (TCTR20210226002).

Immunogenicity following an additional dose of Coronavirus disease 2019 (COVID‐19) vaccine was investigated in an extended primary series among kidney transplant (KT) recipients. Eighty‐five KT participants were randomized to receive either an mRNA (M group; n = 43) or viral vector (V group; n = 42) vaccine. Among them, 62% were male, with a median (IQR) age of 50 (43–59) years and post‐transplantation duration of 46 (26–82) months. At 2 weeks post‐additional dose, there was no difference in the seroconversion rate between the M and V groups (70% vs. 65%, p = .63). A median (IQR) of anti‐RBD antibody level was not statistically different between the M group compared with the V group (51.8 [5.1–591] vs. 28.5 [2.9–119.3] BAU/ml, p = .18). Furthermore, the percentage of participants with positive SARS‐CoV‐2 surrogate virus neutralization test results was not statistically different between groups (20% vs. 15%, p = .40). S1‐specific T cell and RBD‐specific B cell responses were also comparable between the M and V groups (230 [41–420] vs. 268 [118–510], p = .65 and 2 [0–10] vs. 2 [0–13] spot‐forming units/10 6 peripheral blood mononuclear cells, p = .60). In conclusion, compared with an additional dose of viral vector COVID‐19 vaccine, a dose of mRNA COVID‐19 vaccine did not elicit significantly different responses in KT recipients, regarding either humoral or cell‐mediated immunity. (TCTR20211102003).

We presented an initial pilot study report focused on immunogenicity and safety following an inactivated whole virus severe acute respiratory syndrome coronavirus 2 vaccination among kidney transplant (KT) recipients. At four weeks after the first dose of vaccine, the level of anti RBD IgG antibody was not significantly different compared to before vaccination in 30 KT recipients (p = 0.45). Moreover, a significant lower mean (95% CI) anti RBD IgG antibody was observed compared to 30 immunocompetent controls (2.4 [95% CI 1.3 to 3.5] vs. 173.1 [95% CI 88.3-2,457.9] AU/mL, p < 0.001). Mild adverse events included fever (17%) and localized pain at the injection site (14%) were observed after vaccination.

BACKGROUND AND AIMS Patients with end-stage kidney disease (ESKD) are at risk of coronavirus disease 2019 infection and its associated complications. A previous study demonstrated that patients with ESKD on dialysis generated suboptimal humoral immune response (HIR) and lower seroconversion rate after two-dose inactivated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination as compared to healthy individuals. In this study, we examined HIR of the additional dose of ChAdOx1 nCoV-19 vaccine following a standard two-dose inactivated whole-virus SARS-CoV-2 vaccination in patients on dialysis, and compared to those of healthy controls. METHOD We recruited 59 patients with ESKD [31 patients on haemodialysis (HD) and 28 on peritoneal dialysis (PD)) and 16 healthy controls who received two doses of inactivated SARS-CoV-2 vaccine (V2) from Ramathibodi hospital and Banphaeo General Hospital, Bangkok, Thailand, from July 2021 to September 2021. All participants were administered a third dose of the ChAdOx1nCoV-19 vaccine (V3) with a 6-week interval between the V2 to V3. HIR was measured 2 weeks after V2 and V3 using SARS-CoV-2 immunoglobulin G (IgG) assay, which detects antibodies against the S1 receptor-binding domain (RBD) of the SARS-CoV-2 spike protein. Median anti-RBD IgG titer and seroconversion rate, defined as anti-RBD IgG titre ≥ 7.1 BAU/mL, were compared among ESKD patients and to those of healthy controls using the Kruskal–Wallis H test and the chi-squared test, respectively. RESULTS Baseline characteristics of patients on HD, PD and healthy controls are shown in Table 1. Demographic characteristics and baseline laboratory parameters were comparable between the HD and PD groups, except for a lower mean serum albumin level in the PD group (P &lt; .001). None of the healthy controls were immunocompromised or receiving immunosuppressive therapies. At 2 weeks after V3, the median anti-RBD IgG titres were significantly increased in all groups compared to those levels after V2 (85[33–412] versus 1566 [861–3083] BAU/mL for patients on HD, 81 [15–144] versus 913 [293–1359] BAU/mL for patients on PD and 250 [92–603] versus 2210 [1531–2782] BAU/mL for healthy controls; P &lt; .001 for all groups). Comparing antibody levels between groups after V3, patients on PD generated significantly lower anti-RBD IgG titer than patients on HD (P = .02) and healthy controls (P &lt; .01) (Figure 1A). The seroconversion rate of the HD and PD groups improved from 94% and 82% after V2 to 100% after V3 in both groups (P = .16 and P = .03, respectively) (Figure 1B). All patients on dialysis who had anti-RBD IgG &lt; 7.1 BAU/mL after V2 (7/59 patients) seroconverted after the additional dose of ChAdOx1 nCoV-19 vaccine. CONCLUSION We suggest that an additional ChAdOx1 nCoV-19 vaccine after a primary two doses inactivated SARS-CoV-2 vaccination could improve seroconversion rate and magnitude of humoral immune response in patients on dialysis. The durability of the immune response to this vaccination regimen requires further study.

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 non-transplant 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 age of KT recipients was 50 years (IQR, 42 to 54) and 89% were receiving calcineurin inhibitors/mycophenolate/corticosteroid regimens. The median time since transplant was 4.5 years (IQR, 2 to 9.5). Among 35 KT patients, anti-RBD IgG titer after vaccination was not significantly different to baseline, but was significantly lower than in controls (7.8 [95%CI 0.2 to 15.5] vs 2,691 [95%CI 1,581 to 3,802], p<0.001) as well as the percentage of surrogate virus neutralizing antibody inhibition (2 [95% CI -1 to 6] vs 71 [95%CI 61 to 81], p<0.001). However, the mean of SARS-CoV-2 mixed peptides-specific T-cell responses measured by enzyme-linked immunospot assays was significantly increased compared with baseline (66 [95%CI 36 to 99] vs. 34 [95%CI 19 to 50] T-cells/10^6 PBMCs, p=0.02) and comparable to that in controls. Our findings revealed weak HMI and marginal CMI responses in fully vaccinated KT recipients receiving inactivated SARS-CoV-2 vaccine. (Thai Clinical Trials Registry, TCTR20210226002).