Seroconversion after COVID-19 vaccination in patients awaiting liver transplant: fact or fancy?

INTRODUCTION: Chronic liver disease increased the risk of severe COVID-19. Trials to assess efficacy/safety of COVID-19 vaccines in liver disease are under way. We aimed to evaluate humoral immune response and safety of mRNA anti-SARS-CoV-2 vaccination among patients listed for liver transplantation (LT). METHODS: We enrolled as study group, all adult patients awaiting LT in our Center, who completed anti-SARS-CoV-2 mRNA vaccination between January-August 2021. The subjects with history of COVID-19 received one vaccine dose, all the others two doses. All the subjects were tested for SARS-CoV-2 IgG (Liaison® SARS-CoV-2 TrimericS IgG) within one and two months after vaccination. Safety was evaluated with telephone interviews/outpatient visits. A control group of thirty healthcare workers who underwent mRNA vaccination in January 2021 and tested IgG after 4 months was included. RESULTS: In the 89 pre-LT patients, at T1 (after 23 days from vaccination) the seroconversion rate was 94.4%, median IgG value 1980 BAU/mL (interquartile 646-2080); at T2 (after 68 days from vaccination) the rate was 92.0%, IgG value 1450 (577-2080) (T1vsT2, p=0.38). In the 10/89 patients who received one vaccine dose, the median IgG value was 274 (68-548) before vaccine, 2080 (1165-2080) at T1 and 2030 (964-2080) at T2; T0vsT1 p=0.03; T1vsT2 p=0.99. All control group's subjects tested positive at 4 months after vaccination, median value 847 (509-1165) (p<0.001 vsT1 and p=0.04 vsT2 of study group). No serious adverse event was reported in both groups. CONCLUSIONS: Our data from 89 patients awaiting LT suggest a high rate of immunization (94.4%) after a median time of 23 days from safe mRNA COVID-19 vaccine. None of them developed COVID-19. Persistence of humoral response should be monitored over time.