IntroductionThe mRNA‐based vaccine was released as a COVID‐19 prophylactic; however, its efficacy in organ transplant recipients is unknown. This study aimed to clarify this in liver transplant recipients.MethodsHerein, liver transplant recipients from two hospitals who received vaccines were included. Immunoglobulin‐G antibodies against the spike and nucleocapsid proteins were measured chronologically after the second, third, and fourth vaccine doses.ResultsAntibody levels in 125 liver transplant recipients and 20 healthy volunteers were analyzed. The median age at transplant was 35 (interquartile range 1, 53) years, and the period between transplant and the first dose was 15.2 ± 7.7 years. After the second and third doses, 89.1% and 100% of recipients displayed a positive humoral response, respectively. Anti‐spike antibodies after the second dose were significantly reduced at 3 and 6 months, compared to that at 1 month (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). However, a booster vaccine significantly elevated anti‐spike antibodies in LT recipients (p < 0.0001) as well as in healthy controls (p < 0.0001). Additionally, the decay rate was comparable between the transplant recipients and controls (2.1 [0.8, 4.5] vs. 2.7 [1.1, 4.1] AU/mL/day, p = 0.9359). Only 4.0% of vaccinated transplant recipients were positive for anti‐nucleocapsid antibodies.ConclusionLiver transplant recipients can acquire immunity similar to that of healthy people through vaccination against SARS‐CoV‐2. The antibody decay rate is the same, and booster vaccinations should be administered similarly to that in healthy individuals.

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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 SARS-CoV-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 significantly 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 independent 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.

Background: Children who require liver transplantation (LTx) for end-stage liver disease generally have severe growth retardation. After LTx, recipients experience catch-up growth (CUG), though there are not a few cases resulting in short adult height. The aim of the study was to determine decades-long CUG trends and risk factors for short adult height after pediatric LTx. Methods: We examined long-term trends of height Z-score (normalized with the mean of the values is 0 and the standard deviation is 1 using age-and sex-specific references for the general population) in a single-center retrospective cohort of 117 pediatric LTx recipients survived >5 years. The risk factor analysis for short adult height were performed on 75 patients who reached adult height. Results:The median age at LTx was 1.3 years and most primary diagnoses were biliary atresia (77%). Mean height Z-score of pre-LTx and 1, 2, 5 and 8 years after LTx were -2.26, -1.59, -0.91 and -0.59, respectively. After that point, the data plateaued until 20 years. Mean final adult height Z-score was -0.87. In the multivariate analysis, older age at LTx (odds ratio [OR], 1.22 by 1 year; 95% confidence interval [CI], 1.06-1.40; P=0.002), lower height Z-score at LTx (OR, 0.46 by 1 point; 95% CI, 0.29-0.71; P<0.001) and post-LTx hospital stay 60 days (OR, 4.95; 95% CI, P=0.015) were identified as independent risk factors for short adult height. Conclusions: Marvelous CUG was observed after LTx, nevertheless the final adult height was inadequate. For healthy physical growth, LTx should be performed as young as possible and without severe growth retardation, and if growth is inadequate after LTx, use of recombinant human growth hormone might need to achieve proper adult height.

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