Korean J Transplant.  2022 Nov;36(Supple 1):S333. 10.4285/ATW2022.F-4766.

Analysis of antibody responses after COVID-19 vaccination in liver transplant recipients: a single center study

• Oh YJ
• Kim JM
• Choi GS
• Rhu J
• Joh JW
• Kang ES

• KMID: 2535560
• DOI: http://doi.org/10.4285/ATW2022.F-4766

Abstract

Background
Liver transplant (LT) recipients are considered a vulnerable population during the COVID-19 pandemic. The clin-ical efficacy of the COVID-19 vaccine is unknown in immunocompromised patients. The purpose of this study is to give evi-dence of antibody responses after COVID-19 vaccination in LT recipients.
Methods
A total of 46 patients who underwent LT at Samsung Medical Center (SMC, Seoul, Korea) were enrolled before the implementation of the first-dose vaccine in Korea. Those who completed the second dose COVID-19 vaccine between August 2021 and September 2021 were included and followed up through December 2021. Semiquantitative anti-spike serologic test-ing was undertaken with the Roche Elecsys anti-SARS-CoV-2 S enzyme immunoassay, positive cutoff of at least 0.8 U/mL. This study was approved by the SMC institutional review board and participants provided informed consent electronically.
Results
Among all 46 participants, 40 participants (87%) had antibody response after second dose COVID-19 vaccine; 6 (13%) had no antibody response after second dose. The average transplant period for patients with high antibody titers was 9.4±5.0 years, which was longer than those with low antibody titer (2.3±2.8 years) and was statistically significant (P<0.001). Among antibody response group, median (interquartile range [IQR]) trough level of tacrolimus after second dose COVID-19 vaccine were 2.5 (1.6–3.3) and 2.3 (1.6–3.2) before vaccination. Among low antibody response group, median (IQR) trough level of tac-rolimus after second dose COVID-19 vaccine and before vaccination were 5.7 (4.2–7.2) and 7.0 (3.7–7.8) respectively.
Conclusions
Higher trough level of tacrolimus early after transplantation make the vaccine less effective in liver transplant patients. Booster vaccinations are required, especially for patients in the early stage after liver transplantation with compromised immune function.