Transient Hepatitis B Surface Antigenemia Following Immunization with the Adjuvanted Hepatitis B Vaccine Fendrix®

Background: Serological screening for HBV is standard in hemodialysis, and vaccination is recommended for non-immune patients. Objective: To determine the cause of positive HBsAg detected shortly after vaccination. Methods: We conducted a retrospective study in a tertiary hemodialysis unit. Patients with HBsAg reactivity after receiving the adjuvanted HBV vaccine (Fendrix®) were followed with serial serology until HBsAg clearance. Results: Forty-four patients were monitored; seven (15.9%) tested HBsAg-positive 1–7 days post-vaccination, with no evidence of acute hepatitis, prior HBV infection, transplantation, or chronic immunosuppression. Six cleared HBsAg on repeat testing; one remained positive until day 19, with HBsAg as the only marker. Conclusions: Vaccine-related transient HBsAg antigenemia can occur shortly after immunization. Recognizing this phenomenon and timing routine serology appropriately can prevent misinterpretation and unnecessary workups in CKD patients.