Third dose of SARS‐CoV2 mRNA vaccination produces robust persistent cellular and humoral immune responses in liver transplant recipients

Weaker responses have been described after two doses of anti‐SARS‐CoV2 vaccination in liver transplant recipients (LTRs). At the Italian National Institute for Infectious Diseases, 122 LTRs (84% males, median age 64 years) were tested for humoral and cell‐mediated immune response after a third doses of anti‐SARS‐CoV2 mRNA vaccines. Humoral response was measured by quantifying anti‐receptor binding domain and neutralizing antibodies; cell‐mediated response was measured by quantifying IFN‐γ after stimulation of T cells with SARS‐CoV‐2‐specific peptides. Humoral and cellular responses improved significantly compared to the second vaccine dose; 86.4% of previous non‐responders to the first 2 vaccine doses (N = 22) became responders. Mycophenolate mofetil‐containing regimens were not associated with lower response rates to a third vaccine; shorter time since transplantation (<6 years) was associated with lower humoral and cellular responses to third vaccine. Protective antibodies against Omicron variant were detected in 60% of patients 12 weeks after third vaccine dose.