Safety and immunogenicity of HepB-CpG in women with documented pregnancies post-vaccination: A retrospective chart review

Background: There are currently no published data on the use of HepB-CpG (HEPLISAV-B®) during pregnancy or in women with documented pregnancies in the post-vaccination period. We aimed to evaluate data from the clinical development program of HepB-CpG in women who became pregnant during study participation and follow up. Methods: We identified all study participants in the HepB-CpG pivotal pre-licensure clinical trials that had documented pregnancies during study follow up. We measured immunogenicity among study participants in the HepB-CpG (Heplisav-B®) arm compared to the HepB-alum (Engerix-B®) arm of the studies by comparing seroprotection rates (SPRs; anti-HBs ≥ 10 mIU/mL) and geometric mean concentrations (GMCs) of anti-HBs, obtained with FDA approved anti-HBsAg antibody assays at prespecified time points up to 28 weeks of follow up. Pregnancy outcomes were ascertained by chart review of extracted medical records of study participants. Results: We identified 40 documented pregnancies in the HepB-CpG arm and 19 documented pregnancies in the HepB-alum arm. Among subjects with documentation of seroprotection rates, 97.2% (95% CI 85.5–99.9) were seroprotected in the HepB-CpG arm and 66.7% (95% CI 41.0–86.7) were seroprotected in the HepB-alum arm. In the HepB-CpG arm, thirty-six study participants from the pivotal trials had reported pregnancy outcomes, the majority, 21/36 (58%) had a healthy term delivery, with 3/36 (8%) with spontaneous abortions, 1/36 (3%) congenital anomaly, and 2/36 (6%) had preterm birth. In the HepB-alum arm, 10/17 (59%) had healthy term deliveries, with 2/17 (12%) had spontaneous abortions and 1/17 (6%) had congenital anomaly. Conclusions: These limited data suggest that HepB-CpG is immunogenic in women who become pregnant after vaccination, and pregnancy outcomes appear to be similar to women who received HepB-alum prior to pregnancy. These results need to be further verified with larger prospective studies with HBV vaccine administration during pregnancy.