Immunogenicity of 2 Versus 3 Doses of Combined Hepatitis B Vaccines in 2-18 Months Old Children

In the province of Quebec, Canada, hepatitis B vaccination of infants involves three doses of vaccine, 2, 4 and 18 months of age. However, in the current epidemiological context (virtual absence of new cases in young Quebecers) and taking into account scientific data which consistently show a high immunogenicity and efficacy of two doses of hepatitis B vaccine, the relevance of the second dose given at the age of 4 months is questionable.

this study is designed to compare the immunogenicity of the hepatitis B component in children vaccinated with (I) two doses of Infanrix-hexa administered at 2 and 12 months of age versus (II) one dose of Infanrix-hexa and one dose of Twinrix administered respectively at 2 and 12 months of age versus (III) three doses of Infanrix-hexa administered at 2, 4 and 18 months of age (comparator).

Inclusion criteria

• Comparator group :
• Have received 3 doses of Infanrix-hexa as part of the regular vaccination program at the age of 2, 4 and 18 months.
• Study groups:
• Have received 1 dose of Infanrix-hexa as part of the regular vaccination program at the age of 2 months.

Exclusion criteria

• Have received other doses of hepatitis B vaccine;
• Considered immunosuppressed;
• Have an autoimmune disease;
• Have contraindications to HBV vaccination, as defined in the Quebec Immunization Protocol;
• Have a bleeding disorder;

• Have a significant developmental delay;
• Have or plan to participate in other clinical studies with vaccines or products not licensed in Canada;
• Have presented a serious clinical condition to the vaccines administered as part of the study.