Immunogenicity of COVID-19 Vaccines in Chronic Liver Disease Patients and Liver Transplant Recipients: A Systematic Review and Meta-Analysis

Background: Chronic liver disease (CLD) patients and liver transplant (LT) recipients have an increased risk of morbidity and mortality from coronavirus disease 2019 (COVID-19). The immunogenicity of COVID-19 vaccines in CLD patients and LT recipients is poorly understood. The present study aimed to evaluate the immunogenicity of COVID-19 vaccines in CLD patients and LT recipients.Methods: We searched electronic databases for eligible studies published between December 2019 and December 2021. We assessed the risk of bias and conducted the meta-analysis using a random-effects model.Findings: In total, 16 observational studies involving 2531 patients met the inclusion criteria. The pooled rates of humoral immune response after two doses of COVID-19 vaccination in CLD patients and LT recipients were 92% (95% confidence interval (CI)=86%-99%) and 67% (95% CI=59%-74%), respectively. After two doses of vaccination, the humoral immune response rate was similar in CLD patients and healthy controls (risk ratio (RR) =0.93; 95% CI=0.86–1.01; P=0.15). In contrast, LT recipients had a lower humoral immune response rate after two doses of vaccination than healthy controls (RR =0.68; 95% CI=0.59–0.77; P<0.01). In addition, the rate of cellular immune response after two doses of vaccination in LT recipients was 66% (95% CI=30%-102%).Interpretation: Our meta-analysis demonstrated that COVID-19 vaccination induced reduced cellular and humoral immune responses in LT recipients but good humoral immune responses in CLD patients. These findings indicate that both populations should complete the full vaccine schedule without delay and support the administration of a third dose of vaccine to LT recipients. Further studies examining the immunogenicity of the various types of vaccines, as well as updated living meta-analyses, are warranted.Funding Information: None. Declaration of Interests: The authors of this manuscript have no conflicts of interest to disclose.