Uptake and safety of Hepatitis B vaccination during pregnancy: A Vaccine Safety Datalink study.

INTRODUCTION: Hepatitis B virus (HBV) infection acquired during pregnancy can pose a risk to the infant at birth that can lead to significant and lifelong morbidity. Hepatitis B vaccine (HepB) is recommended for anyone at increased risk for contracting HBV infection, including pregnant women. Limited data are available on the safety of HepB administration during pregnancy. OBJECTIVES: To assess the frequency of maternal HepB receipt among pregnant women and evaluate the potential association between maternal vaccination and pre-specified maternal and infant safety outcomes. METHODS: We examined a retrospective cohort of pregnancies in the Vaccine Safety Datalink (VSD) resulting in live birth outcomes from 2004 through 2015. Eligible pregnancies in women aged 12-55 years who were continuously enrolled from 6 months pre-pregnancy to 6 weeks postpartum in VSD integrated health systems were included. We compared pregnancies with HepB exposure to those with other vaccine exposures, and to those with no vaccine exposures. High-risk conditions for contracting HBV infection were identified up to one-year prior to or during the pregnancy using ICD-9 codes. Maternal and fetal adverse events were also evaluated according to maternal HepB exposure status. RESULTS: Among over 650,000 pregnancies in the study period, HepB was administered at a rate of 2.1 per 1000 pregnancies (n = 1399), commonly within the first 5 weeks of pregnancy. Less than 3% of the HepB-exposed group had a high-risk ICD-9 code indicating need for HepB; this was similar to the rate among HepB unvaccinated groups. There were no significant associations between HepB exposure during pregnancy and gestational hypertension, gestational diabetes, pre-eclampsia/eclampsia, cesarean delivery, pre-term delivery, low birthweight or small for gestational age infants. CONCLUSIONS: Most women who received maternal HepB did not have high-risk indications for vaccination. No increased risk for the adverse events that were examined were observed among women who received maternal HepB or their offspring.

Effect of adjuvant on pharmacokinetics, organ distribution and humoral immunity of hepatitis B surface antigen after intramuscular injection to rats.

Two types of radioiodinated plasma driven antigens, heat-inactivated (¹²5I-h-HBsAg) and formalin-inactivated HBsAg (¹²5I-f-HBsAg) were investigated for the effect of immunoadjuvant, aluminium phosphate (AP) on pharmacokinetics, organ distribution and humoral immunity of differently inactivated hepatitis B surface antigens (HBsAg) in rats. As a result, most of h-HBsAg (90%) was retained and slowly eliminated from the injection site. The h-HBsAg was highly localized in regional lymph node (RLN), but resulted in low humoral immune response. On the other hand, f-HBsAg was less localized in the injection site and RLN, but mainly distributed into serum and liver (62.9 and 22.4%, respectively). However, both h-HBsAg and f-HBsAg slowly disappeared from the injection site with AP, resulting in the increased area under the amount-time curve (AUQ) of h-HBsAg and f-HBsAg in the injection site. Exposures of h-HBsAg and f-HBsAg in serum were increased (1.4 and 2.8 times increase in AUC, respectively) with AP. The RLN uptake of both antigens were dramatically increased (25 and 3.1 times increase in AUC, respectively) with higher humoral immune response. The antibody titres were also increased with AP. In conclusion, pharmacokinetics, organ distribution and humoral immunity of h-HBsAg were highly dependent on the inactivation method of antigen and the presence of immunoadjuvant such as AP.

Pharmaceutical and immunological evaluation of a single-shot hepatitis B vaccine formulated with PLGA microspheres.

A single-shot Hepatitis B vaccine formulation using poly(d,l)-lactide-co-glycolide acid (PLGA) microspheres as a delivery system was examined using a variety of biophysical and biochemical techniques as well as immunological evaluation in C3H mice. PLGA microsphere encapsulation of the Hepatitis B surface antigen (HBsAg), a lipoprotein particle, resulted in good recoveries of protein mass, protein particle conformational integrity, and in vitro antigenicity. Some partial delipidation of the HBsAg, however, was observed. The loading and encapsulation efficiency of HBsAg into the PLGA microspheres were measured along with the morphology and size distribution of the vaccine-loaded PLGA microspheres. The in vitro release kinetics of HBsAg from the PLGA microspheres was evaluated and found to be affected by experimental conditions such as stirring rate. HBsAg showed enhanced storage stability at 37 degrees C in the slightly acidic pH range reported to be found inside PLGA microspheres; thus, the antigen is relatively stable under conditions of temperature and pH that may mimic in vivo conditions. The immunogenicity of the microsphere formulations of HBsAg was compared with conventional aluminum adjuvant formulated HBsAg vaccine in C3H mice. Comparisons were made between aluminum formulations (one and two injections), PLGA microsphere formulations (single injection), and a mixture of aluminum and PLGA microsphere formulations (single injection). The nine-month serum antibody titers indicate that a single injection of a mixture of aluminum and PLGA-formulated HBsAg results in equal or better immune responses than two injections of aluminum-formulated HBsAg vaccine. Based on these in vitro and in vivo studies, it is concluded that HBsAg can be successfully encapsulated and recovered from the PLGA microspheres and a mixture of aluminum-adjuvanted and PLGA-formulated HBsAg can auto-boost an immune response in manner comparable to multiple injections of an aluminum-formulated vaccine.