Hepatitis B Reactivation Following COVID-19

We describe the case of a 83-year-old man who received an allogenic stem cell transplant for acute myelogenous leukemia in 2010. He developed mild COVID-19 illness in 2023 and improved without corticosteroids. Elevated serum transaminase levels were noted, with subsequent evaluation showing a hepatitis B virus (HBV) DNA level measured by polymerase chain reaction of 297 000 000 IU/mL, and positive hepatitis B surface antigen (HBsAg), hepatitis B e antigen (HBeAg), and hepatitis B core antibody (anti-HBc). At baseline, he had a positive anti-HBc and a negative HBsAg. He was treated with entecavir and showed improvement in HBV DNA polymerase chain reaction and serum transaminase levels. Patients with COVID-19 who have persistently elevated serum transaminase levels should be evaluated for HBV reactivation.