Crosby, Sheena K

INTRODUCTION: Hepatitis B virus (HBV) vaccination is recommended in patients with inflammatory bowel disease (IBD). Although the 2-dose Heplisav-B vaccine has proven effective, more than 20% of patients with IBD do not seroconvert. We prospectively evaluated the effectiveness of a third Heplisav-B dose in patients with IBD lacking HBV immunity despite 2-dose vaccination. METHODS: Adults with IBD who had received 2-dose Heplisav-B vaccination between 2018 and 2023 were identified. Seroconversion was defined as hepatitis B surface antibody (HBsAb) ≥ 10 IU/L measured at ≥4 weeks after vaccination. Patients who did not seroconvert were prospectively offered a third Heplisav-B dose, followed by repeat HBsAb measurement. Demographic, clinical, medication, and vaccination data were compared between those who did and did not seroconvert. RESULTS: Of 192 patients identified, 71.9% (138/192) seroconverted after 2-dose Heplisav-B vaccination. The 54 patients (28.1%) who did not seroconvert were more likely to be male, have diabetes, chronic kidney disease, or elevated Charlson Comorbidity Index. Of the 54 patients, 30 (55.6%) elected to receive a third Heplisav-B dose, with 56.7% (17/30) achieving seroconversion (median HBsAb titer 376 IU/L, IQR 47–1,000 IU/L) despite a median intervaccination time of 416 days (IQR 90.8–667.8). No differences were noted between patients who did vs did not seroconvert after third-dose vaccination. DISCUSSION: In patients with IBD lacking HBV immunity despite 2-dose Heplisav-B vaccination, administration of a third dose resulted in a 56.7% seroconversion rate. Our results suggest that administration of an additional Heplisav-B dose may be an effective strategy in patients lacking immunity despite primary 2-dose vaccination.