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Pharmacology: Pharmacodynamics: Engerix-B induces specific humoral antibodies against HBsAg (anti-HBs antibodies). Anti-HBs antibody concentrations ≥ 10 mIU/ml correlates with protection to HBV infection.
Protective efficacy and long-term immune response: At risk groups: In field studies, a protective efficacy between 95% and 100% was demonstrated in neonates, children and adults at risk.
A 95% protective efficacy was demonstrated in neonates of HBeAg positive mothers, immunised according to the 0, 1, 2 and 12 or 0, 1 and 6 schedules without the concomitant administration of HBIg at birth. However, simultaneous administration of HBIg and vaccine at birth increased the protective efficacy to 98%.
Twenty years after primary vaccination during infancy, subjects born to mothers who were HBV carriers, received a challenge dose of Engerix-B. One month later, at least 93% of subjects (N=75) mounted an anamnestic response demonstrating immune memory.
Healthy subjects: The table as follows summarizes seroprotection rates (i.e. percentages of subjects with anti-HBs antibody concentrations ≥ 10 mIU/ml) obtained in clinical studies with the different schedules mentioned in Dosage & Administration: (See Table 1).
Click on icon to see table/diagram/imageThe long-term immune response was assessed in a clinical trial in subjects from 11 years up to and including 15 years of age at the time of primary vaccination. The seroprotection rates obtained with the two different dosages and schedules were evaluated up to 66 months after the first dose of the primary vaccination and are presented in the table as follows: (See Table 2).
Click on icon to see table/diagram/imageThese data show that a primary vaccination with Engerix-B vaccine induces circulating anti-HBs antibodies that persist for at least 66 months. After having completed the primary course, at each time point there is no clinically significant difference in the seroprotection rates when comparing the 2 vaccine groups.
All subjects in both vaccine groups (including subjects with anti-HBs antibody concentrations < 10 mIU/ml) received a challenge dose 72 to 78 months after primary vaccination. One month after the challenge dose, all subjects mounted an anamnestic response to the challenge dose and were shown to be seroprotected (i.e. anti-HBs antibody concentrations ≥ 10 mIU/ml). These data suggest that protection against hepatitis B may still be conferred through immune memory in all subjects who responded to primary vaccination but lost seroprotection level of anti-HBs antibodies.
Long-term persistence was assessed in a clinical study in subjects (N=292) aged 15 to 16 years, vaccinated in the first 2 years of life with 3 doses of Engerix B. The anti-HBs seroprotection was 65.4% at 14 years [range 13.5-15.5 years] after primary vaccination. At this time point, all subjects (including subjects with anti-HBs antibody concentrations < 10 mIU/ml) received a challenge dose. One month after the challenge dose, 97.9% of subjects were shown to be seroprotected. An anamnestic response was observed in 92.9% of subjects seronegative before the challenge dose (N=84) and in 98.6% of subjects seropositive before the challenge dose (N=207).
Patients with renal insufficiency including patients undergoing haemodialysis: (See Table 3).
Click on icon to see table/diagram/imagePatients with type II diabetes: (See Table 4).
Click on icon to see table/diagram/imageReduction in the incidence of hepatocellular carcinoma in children: A significant reduction in the incidence of hepatocellular carcinoma has been observed in children aged 6-14 years following a nationwide hepatitis B vaccination in Taiwan. There was a significant decline in the prevalence of hepatitis B antigen, the persistence of which is an essential factor in the development of hepatocellular carcinoma.
Toxicology: Non-Clinical Information: Appropriate safety tests have been performed.
