Liver and Bile
J Hepatol. 2022;77(3):702–9
A third dose of the BNT162b2 mRNA vaccine significantly improves immune responses among liver transplant recipients
Background and aims: Immune responses of solid organ transplant recipients to 2 doses of the BNT162b2 mRNA anti-SARS-CoV-2 vaccine are impaired. The immunogenicity and safety of a third dose among liver transplant (LT) recipients are unknown. This work aimed to evaluate the immune response of LT recipients to a third dose of the BNT162b2 mRNA vaccine.
Methods: Consecutive LT recipients (n = 61) in follow-up at Sheba Medical Center were included. Receptor-binding domain (RBD) immunoglobulin (Ig)G, neutralizing antibody titers, and T-cell levels before and 21–28 days after a third vaccine dose were determined. Adverse effects after the third dose were monitored.
Results: The median age of LT recipients was 65 years and 57.4% were male. The humoral immune response rate improved significantly, with 56% of patients showing a response before the third vaccine dose compared to 98% after the third dose. The cellular response in 12 evaluated patients improved significantly (p = 0.008). The geometric mean of anti-RBD IgG levels, neutralizing antibody levels, and T-cell count also increased significantly after the third dose. Neutralizing antibody titers after the third dose negatively correlated with age (p = 0.03), mycophenolate mofetil treatment (p = 0.005), and combined immunosuppression as opposed to calcineurin inhibitor monotherapy (p = 0.001). After the third dose, adverse effects were reported by 37% of recipients and were mostly mild (local pain and fatigue).
Conclusion: After a third BNT162b2 mRNA vaccine, the immune response improved significantly among liver transplant recipients, without serious adverse effects. Further studies are needed to evaluate immune response durability and to determine the optimal number and schedule of booster vaccine doses.