Coronavirus disease 2019 (COVID-19) vaccination in immunocompromised, especially transplant recipients, may induce a weaker immune response. But there are limited data on the immune response after
COVID-19 vaccination in
liver transplant (LT) recipients, especially on the comparison of Ab responses after different
vaccine platforms between
mRNA and adenoviral vector
vaccines. Thus, we conducted a prospective study on LT recipients who received two doses of the
ChAdOx1 nCoV-19 (ChAdOx1),
mRNA-1273, or
BNT162b2 vaccines compared with healthy healthcare workers (HCWs). SARS-CoV-2 S1-specific
IgG Ab titers were measured using ELISA. Overall, 89 LT recipients (ChAdOx1, n=16 [18%]) or
mRNA vaccines (
mRNA-1273 vaccine, n=23 [26%];
BNT162b2 vaccine, n=50 [56%]) received 3 different
vaccines. Of them, 16 (18%) had a positive Ab response after one dose of
COVID-19 vaccine and 62 (73%) after 2 doses. However, the median Ab titer after two doses of
mRNA vaccines was significantly higher (44.6 IU/ml) than after two doses of ChAdOx1 (19.2 IU/ml, p=0.04). The longer time interval from
transplantation was significantly associated with high Ab titers after two doses of
vaccine (p=0.003). However,
mycophenolic acid use was not associated with Ab titers (p=0.53). In conclusion, about 3-quarters of LT recipients had a positive Ab response after 2 doses of
vaccine, and the
mRNA vaccines induced higher Ab responses than the ChAdOx1
vaccine.