Analysis of Acquisition of COVID-2019 Neutralizing Antibodies in Organ Transplant Recipients.

Background: This study confirmed the kinetics of antibodies acquired by SARS-CoV-2 vaccination in solid-organ transplant recipients and examined their association with the development of COVID-19 and immunosuppressive status in organ transplant recipients.

Methods: We measured COVID-19 neutralizing antibody titer in 21 organ transplant recipients vaccinated with the COVID-19 vaccine and 14 nontransplant recipients (control group) 3 times before and at 1 and 6 months after the third dose of vaccine. By confirming the kinetics of the acquired antibodies, we examined the relevance of the background characteristics of organ transplant recipients, such as the development of infectious diseases and immunosuppressive status.

Results: The proportion of patients with neutralizing antibodies was significantly higher in the nontransplant group than in the transplant group. Neutralizing antibody titers were significantly lower in transplant recipients when they were compared before the third dose and 1 month later. In the transplant recipient group, 11 patients were positive, and 10 were negative for neutralizing antibodies. When the causal relationship between the neutralizing antibody titer and background was examined, a positive correlation was found between the antibody titer and the number of years since transplantation, and a negative correlation was found between the tacrolimus trough values, amount of mycophenolate mofetil or steroids taken internally, and antibody titer.

Conclusion: This study suggests that the effectiveness of vaccination in transplant recipients is associated with the post-transplant period before vaccination and the dose of immunosuppressive agents.