Korean J Transplant.  2022 Nov;36(Supple 1):S104. 10.4285/ATW2022.F-2222.

Antibody titer after COVID-19 vaccination in liver transplant recipients

• Mita A
• Shimizu A
• Ohno Y
• Kubota K
• Masuda Y
• Notake T
• Yoshizawa K
• Soejima Y

• KMID: 2535620
• DOI: http://doi.org/10.4285/ATW2022.F-2222

Abstract

Background
COVID-19 has raised a pandemic. A mRNA-based vaccine is released for prophylaxis, and its high efficacy has been reported. However, there is a paucity of data in immunosuppressed individuals. We estimated the serum antibody (Ab) titer after vaccination in liver transplant (LT) recipients.
Methods
The LT recipients who took vaccination were included in this study. Twice vaccination was performed and SARSCoV-2 S-IgG Ab titer was measured 1, 3, 6 months after the second dose of vaccination.
Results
We measured Ab titer in 107 LT recipients which entered for this study by July 11, 2022. A median age at LT was 34 (interquartile range, 2–53) years old, an observation period was 15.0±7.9 years, and a period between LT and the first dose was 15.2±11.2 years. Posttransplant immunosuppression regimen included calcineurin inhibitor (n=104, 89.7%), mycophenolate mofetil (MMF) (n=33, 30.8%), steroid (n=21, 19.6%) and mTOR inhibitor (n=6, 5.6%) at the time of the first dose. Recipients took single reagent (n=65), 2 reagents (n=28), 3 reagents (n=13) and 4 reagents (n=1). An Ab titer 3 and 6 months after was signifi-cantly reduced than that 1 month after (26.0 [5.4, 59.5], 14.7 [6.5, 31.4] vs. 59.7 [18.3, 164.0] AU/mL, respectively; P<0.0001). The Ab titers 6 months after in LT recipients were comparable to those in healthy volunteer (n=20, 12.2 [7.7, 20.0]; P=0.5120). Multi-variate regression analysis identified age at LT <37 years old and a period between LT and the 1st dose >12.3 years as in-dependent predictors for positive SARS-CoV-2 S-IgG Ab titer after 2nd dose.
Conclusions
Acquired acquisition rate after two doses of SARS-CoV-2 Vac was relatively good (89%) in LT recipients. However, An Ab titer rapidly decreased after vaccination. LT recipients could also obtain acquired acquisition by vaccination as well as healthy people.