hepatitis b virus infection flare induced acute-on-chronic liver failure after covid-19 vaccination: a case report

Introduction: during the coronavirus disease 2019 (covid-19) pandemic, covid-19 vaccination is essential for controlling the outbreak and preventing severe disease. however, there are still uncertainties about the safety of covid-19 vaccination in individuals with chronic liver disease. case presentation: three patients with hepatitis b virus (hbv) infection presented to our hospital with acute-on-chronic liver failure (aclf) due to hbv flare after covid-19 vaccination (mrna-1273 and chadox1 ncov-19). their covid-19 antibodies were tested by elecsys anti-sars-cov-2 s immunoassay, which showed good response after full two-dose course of vaccine. one patient refused the test. the patients’ clinical conditions deteriorated during hospitalization. patient 1 received entecavir (baraclude) 1 mg/day upon presentation, but the serum bilirubin level and international normalized ratio (inr) kept increasing. he was comatose in one week and underwent urgent living donor liver transplantation. patient 2 was on regular entecavir (baraclude) 0.5 mg/day and was increased to 1 mg/day upon admission. the serum bilirubin level and inr kept increasing, and he developed grade 3 hepatic encephalopathy in three weeks. the patient then received urgent living donor liver transplantation. patient 3 received entecavir (baraclude) 1 mg/day upon presentation. her serum bilirubin and inr kept increasing, and her mental status altered in a week. she did not undergo liver transplantation for her old age. conclusions: it is unclear whether there is a cause-and-effect relationship between covid-19 vaccination and hbv infection flare. furthermore, the mechanism of covid-19 vaccine-induced hbv reactivation is not established. further studies are needed in this regard. however, during the covid-19 pandemic, prophylactic antiviral therapy for hbv infection before covid-19 vaccination should be considered.