2-Dose Vaccine Is as Immunogenic as 3 Doses

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Vaccination Against Hepatitis B with a 2-Dose Vaccine Is as Immunogenic as 3 Doses of Engerix-B

The current vaccination schedule with the hepatitis B vaccine includes 3 injections, at T=0, T=1 or 2, and T=6 months, but alternative schedules are under investigation. Reducing the number of required vaccine injections could result in a much more practical vaccination program for a large population.

In recent years, new and more potent adjuvants have been developed and applied for human vaccination. We investigated one of them, SBAS4, which contains 3-deacylated monophosphoryl lipid A and alum (Al(OH)3), for safety and immunogenicity in humans.

Increasing the immunogenicity of the hepatitis B vaccine may lead to a reduction of the number of injections necessary for protection. In this study the researchers compared the safety and immunogenicity of a 2-dose schedule of SBAS4-adjuvanted hepatitis B vaccine with the current 3-dose schedule of Al(OH)3-adjuvanted vaccine (Engerix-B).

A total of 375 subjects were included. In a single-blind, random design the subjects received either Engerix-B at T=0, T=1 and T=6 months, or one of three batches of SBAS4-adjuvanted hepatitis B vaccine at T=0 and T=6 months. At T=1 month a placebo-injection was given. Blood was drawn at T=0, T=1, T=2, T=6 and T=7 months.

Adverse reactions were recorded and antibodies to hepatitis B surface antigen (anti-HBs) were measured in the serum. The subjects were checked for hepatitis B markers in the first serum sample at T=0. Of the 375 inclusions, 21 subjects were not included in the data evaluation.

Of the 354 evaluable subjects, 235 had received SBAS4-adjuvanted hepatitis B vaccine, and 119 had received Engerix-B. Anti-HBs titers after one and after two injections with the SBAS4-adjuvanted vaccine were significantly higher as compared with Engerix-B. Anti-HBs titers one month after two injections with SBAS4-adjuvanted hepatitis B vaccine were significantly higher (p=0.003) than those one month after three injections with Engerix-B.

The percentage of responders after two injections with SBAS4-adjuvanted vaccine were similar to the percentage of responders after three injections with Engerix-B. Local side effects were similar or sometimes slightly more serious with SBAS4-adjuvanted hepatitis B vaccine as compared to Engerix-B.

Conclusion: Two doses with SBAS4-adjuvanted hepatitis B vaccine are at least as immunogenic as three doses of the current Al(OH)3 -adjuvanted vaccine.

01/31/03

Reference
GJ Boland and Others. VACCINATION WITH SBAS4-ADJUVANTED VACCINE AGAINST HEPATITIS B. Abstract 854. 53rd AASLD. November 1-5, 2002. Boston, MA. Hepatology 2002: Vol 36 No 4, Pt 2 of 2.