Immunogenicity and reactogenicity of a trivalent influenza split vaccine in previously unvaccinated children aged 6-9...

Area of Science:

• Pediatrics
• Immunology
• Vaccinology

Background:

• Influenza vaccination is recommended for children.
• Previously unvaccinated children typically require two doses of trivalent inactivated influenza vaccine (TIV).
• The optimal age for administering a second TIV dose requires further investigation.

Purpose of the Study:

• To evaluate the age threshold for administering a second dose of TIV in previously unvaccinated children.
• To assess the immunogenicity and safety of TIV in different pediatric age groups.

Main Methods:

• A cohort of 224 previously unvaccinated children received TIV (Influsplit SSW/Fluarix).
• Children aged 6-9 years (n=110) received two doses 4 weeks apart; children aged 10-13 years (n=114) received a single dose.
• Serum haemagglutination inhibiting (HI) antibody titers were measured pre- and post-vaccination.

Main Results:

• Children aged 10-13 years met CHMP criteria for HI antibody response after one TIV dose.
• Children aged 6-9 years met CHMP criteria after two TIV doses.
• A second dose showed marked benefit in 8-year-old children, even though one dose was sufficient against all strains.

Conclusions:

• TIV (Influsplit SSW/Fluarix) is well-tolerated and highly immunogenic in children.
• Results support the recommendation of two TIV doses for previously unvaccinated children younger than 9 years.
• The study provides evidence for age-specific influenza vaccine dosing strategies.