Changes in antibody titer after four and five doses of the SARS-CoV-2 vaccine in Japanese post-kidney transplant patients.

INTRODUCTION: Immunosuppressed patients exhibit low antibody acquisition rates following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. Kidney transplant recipients previously exhibited low antibody acquisition rates after two vaccine doses, which increased after the third dose. We evaluated antibody titers of Japanese post-kidney transplant patients after the fourth and fifth vaccinations. METHODS: Antibody titers for SARS-CoV-2 spike protein were measured between 3 weeks and 3 months after the fourth or fifth vaccination. RESULTS: Increased antibody acquisition rates were observed after the fourth (75.0% antibody-positive) and fifth (81.5% antibody-positive) vaccinations. The antibody-acquired group after the fourth vaccination exhibited a higher body mass index and estimated glomerular filtration rate (eGFR) than the non-acquired group. A higher eGFR was associated with antibody acquisition after the fifth vaccination. CONCLUSION: In Japanese post-kidney transplant patients, the antibody acquisition rate increased with each vaccine additional dose. Additional vaccinations are recommended to protect against SARS-CoV-2 infection.

Assessment of Antibody-Titer Changes after Second and Third Severe Acute Respiratory Syndrome Coronavirus 2 mRNA Vaccination in Japanese Post-Kidney-Transplant Patients.

Post-renal-transplant patients have a relatively low antibody-acquisition rate following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccination. In this study, antibody titers were measured 5−6 months and 3 weeks to 3 months after the second and third SARS-CoV-2 mRNA vaccinations, respectively. Post-renal-transplant patients visiting our hospital who had received three SARS-CoV-2 mRNA vaccine doses were included in the study. SARS-CoV-2 immunoglobulin G antibody titers were measured three times: between 3 weeks and 3 months after the second vaccination, 5−6 months after the second vaccination, and between 3 weeks and 3 months after the third vaccination. A total of 62 (40 men and 22 women) were included, 44 of whom (71.0%) were antibody positive after their third vaccination. On comparing the antibody-acquired and antibody-non-acquired groups, body mass index (BMI, odds ratio [OR]: 1.44, 95% confidence interval [CI]: 1.07−1.93, p < 0.05) and the estimated glomerular filtration rate (eGFR, OR: 1.14, 95% CI: 1.06−1.24, p < 0.01) were associated with antibody acquisition. Therefore, in Japanese post-kidney-transplant patients, increases in the antibody-acquisition rate and absolute antibody titer after the third vaccination were observed, with BMI and eGFR associated with the antibody-acquisition rate.

Antibody response to double SARS-CoV-2 mRNA vaccination in Japanese kidney transplant recipients.

Immunocompromised patients, especially those who undergo kidney transplantation, have lower antibody levels following SARS-CoV-2 mRNA vaccination. The situation of transplant treatment, such as transplant source and immunosuppressive drugs, is different in Japan than that in other countries. Therefore, it is necessary to clarify whether antibody acquisition rates differ between Japan and other countries. This retrospective study included patients with post-kidney transplant who were attending at the Nagoya University Hospital. The anti-SARS-CoV-2 IgG antibody titers were measured between 3 weeks and 3 months after vaccination. Seventy-three patients (45 men and 28 women) were included. Of these, 23 (31.5%) showed antibody presence, and the rates of antibody acquisition were very low than those in the control group (100.0% vs. 31.5%, P < 0.05). Antibody acquisition rates were associated with body mass index (odds ratio [OR]: 1.21, 95% confidence interval [CI]: 1.04-1.39, P < 0.05) and the duration between transplantation and vaccination (OR: 1.01, 95% CI: 1.00-1.02, P < 0.05). The immunosuppressive drugs used were: prednisolone in all cases, tacrolimus in 89.0%, cyclosporine in 9.6%, and mofetil mycophenolate in 97.3%. None of the patients were excluded from receiving two doses of the vaccine due to adverse effects. The study indicated that vaccination-induced antibody acquisition rates against SARS-CoV-2 were extremely low in Japanese patients who underwent post-kidney transplantation. Thus, despite two doses of vaccination, it is necessary to closely monitor infection control in such patients.