SARS-CoV-2 vaccination in liver transplant recipients: factors affecting immune response and refusal to vaccine

ABSTRACT

Background and aims: The effectiveness of SARS-CoV-2 vaccination in liver transplant (LT) recipients varies between 47.5% to 81% with majority of reports focusing on the immune response assessed in the first month after the vaccination. Data on LT recipients willingness to receive vaccine is limited to only a few reports. Here, we analysed the immune response to the SARS-CoV-2 vaccination, factors affecting response and reasons for refusal to receive this vaccine. Method: Among 300 consecutive LT recipients, 225 (75%) were vaccinated. Seventy-four (25%) subjects were not vaccinated, including 45 (15%) who refused to be vaccinated and 29 (10%) who did not get the vaccine due to medical reasons. The humoral response was assessed by quantitative determination of anti-trimeric spikeprotein- specific-IgG antibodies to SARS-CoV-2 by LIAISON® SARSCoV- 2 TrimericS IgG assay (Diasorin, Italy), which is a chemiluminescence immunoassay (CLIA). Thirty-four vaccinated patients with prior COVID-19 infection were analysed separately. Results: Among 192 LT recipients vaccinated without prior COVID-19, 69% of them had an immune response (median time of 125 days after the second dose). Older age, worse kidney function and dual immunosuppression negatively affected the humoral response. Mycophenolate mofetil increased the risk of non-response (OR 3.0, 95% CI 1.43–6.25). LT recipients with prior COVID-19 presented with a robust immune response (100%) and with significantly higher IgG antibodies (median 2080 vs 134 BAU/ml;p <0.001). The antibodies concentrationwas higher in the first 90 days fromthe second dose (p = 0.034) and stabile when compared between patients who received the vaccination within 90–150 or more than 150 days (Figure 1). Female gender, living in rural area, lower BMI (all p < 0.05) and younger age (p < 0.001) were associated with refusal of the vaccine due to non-medical reasons. In contrast, liver recipients with diabetes and impaired kidney function (both p <0.01)were more prone to get a vaccine. (Figure Presented) Figure Median SARS-CoV-2 TrimericS IgG concentration among liver transplant recipients (without prior COVID-19) compared between time from the second dose of the vaccine <90 days, 90–150 days and >150 days. Conclusion: Lower immune response after the vaccine among LT recipients may support administration of a third dose. Previous COVID-19 infection dramatically improves response to vaccination in these patients. Sociodemographic factors may play a role in refusal of being vaccinated but this finding require further investigations in other cohorts of transplanted patients.