Reduced Neutralization Efficacy against Omicron Variant after Third Boost of BNT162b2 Vaccine among Liver Transplant Recipients

Yana Davidov*, Victoria Indenbaum, Michal Mandelboim, Keren Asraf, Tal Gonen, Keren Tsaraf, Oranit Cohen-Ezra, Mariya Likhter, Ital Nemet, Limor Kliker, Orna Mor, Ram Doolman, Carmit Cohen, Arnon Afek, Yitshak Kreiss, Gili Regev-Yochay, Yaniv Lustig, Ziv Ben-Ari

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The immune responses of liver transplant (LT) recipients after the third boost of the BNT162b2mRNA vaccine improved. This study evaluates the durability of the immune response of LT recipients after the third boost, its predictors, and the impact of emerging variants. The receptor-binding domain IgG was determined at median times of 22 (first test) and 133 days (second test) after the administration of the third boost. IgG antibody titers > 21.4 BAU/mL were defined as a positive response. The neutralization efficacies of the vaccine against the wild-type, Omicron, and Delta variants were compared in the first test. The 59 LT recipients were of a median age of 61 years (range 25–82); 53.5% were male. Following administration of the third dose, the positive immune response decreased from 81.4% to 76.3% between the first and second tests, respectively, (p < 0.0001). The multivariate analysis identified CNI monotherapy (p = 0.02) and hemoglobin > 12 g/dL (p = 0.02) as independent predictors of a maintained positive immune response 133 days after the third dose. The geometric mean titers of Omicron neutralization were significantly lower than the wild-type and Delta virus (21, 137, 128, respectively; p < 0.0001). The immune response after the third BNT162b2mRNA vaccine dose decreased significantly in LT recipients. Further studies are required to evaluate the efficacy of the fourth vaccine dose and the durability of the immune response.

Original languageEnglish
Article number253
Issue number1
StatePublished - Jan 2023


  • BNT162b2 vaccine
  • Omicron
  • liver transplant recipients
  • neutralizing antibody
  • third vaccine dose


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