Immunogenicity of COVID-19 vaccines in chronic liver disease patients and liver transplant recipients: a systematic review and meta-analysis

BACKGROUND AND AIMS: 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. Two reviewers independently conducted the literature search, extracted the data, and assessed the risk of bias and the quality of included studies. The rates of detectable immune response were pooled from single-arm studies. For comparative studies, we compared the rates of detectable immune response between patients and healthy controls. The meta-analysis was conducted using the Stata software with a random-effects model. RESULTS: In total, 19 observational studies involving 4191 participants met the inclusion criteria. The pooled rates of detectable humoral immune response after two doses of COVID-19 vaccination in CLD patients and LT recipients were 95% (95% confidence interval (CI)=88%-99%) and 66% (95% CI=57%-74%), respectively. After two doses of vaccination, the humoral immune response rate was similar in CLD patients and healthy controls (risk ratio (RR)=0.96; 95% CI=0.90-1.02; P=0.14). 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). CONCLUSIONS: Our meta-analysis demonstrated that COVID-19 vaccination induced strong humoral immune responses in CLD patients but poor humoral immune responses in LT recipients.