Hepatitis B reactivation: A possible cause of coronavirus disease 2019 vaccine induced hepatitis

BACKGROUND AND AIMS: Coronavirus disease 2019 (COVID-19) vaccines were rapidly implemented globally and vaccine-associated immune-related hepatitis was recently reported. We aim to investigate its impact in regions endemic of chronic hepatitis B (CHB). METHODS: We retrospectively collected patients who developed hepatitis within 90 days after COVID-19 vaccination in Taiwan. The mechanisms of hepatitis included vaccine induced liver injury (VILI) and immune-related hepatitis, which are direct liver injuries defined as aspartate or alanine aminotransferase (AST or ALT) increased ≥ 5-fold upper limit of normal (ULN) and/or AST or ALT ≥ 3-fold of ULN with concurrent total bilirubin ≥ 2-fold of ULN. Indirect liver injury due to HBV reactivation was defined as HBsAg reverse seroconversion or significant rise in HBV DNA level. The demographics, clinical data, and course of hepatitis were compared statistically. RESULTS: Twenty-five patients were included with a median age of 54. The culprit vaccines were ChAdOx1 nCoV-19 (n = 9), mRNA-1273 (n = 12), and BNT162b2 (n = 4). The characteristics of hepatitis were comparable regardless of vaccine subtypes. The median onset of hepatitis was 25 days post vaccination, with a peak of 10-fold ALT-increase. The etiologies included HBV reactivation (n = 10), VILI (n = 10), and immune-related hepatitis (n = 5). HBV reactivation accounts for 90% of vaccine-induced hepatitis in patients of CHB (n = 10), and two patients died. Patients with initial AST levels >500 U/L increased 27-fold risks of liver injury greater than moderate severity compared with those without. CONCLUSIONS: COVID-19 vaccine induced hepatitis is a clinical significant complication, and HBV reactivation may account for a possible mechanism.