Immunogenicity and safety of MF59-adjuvanted H5N1 influenza vaccine from infancy to adolescence

OBJECTIVE: This study evaluated the immunogenicity, safety, and tolerability of a MF59-adjuvanted H5N1 vaccine in a population 6 months through 17 years of age. METHODS: Healthy subjects 6 to_36 months, 3 to_9 months, and 9 to_18 years of age were assigned randomly to receive 2 doses of either a MF59-adjuvanted H5N1 vaccine (7.5 _g/dose) or a MF59-adjuvanted trivalent seasonal influenza control vaccine (15 _g/dose for each antigen). Immunogenicity against the A/Vietnam/1194/2004-like vaccine strain was measured before and 3 weeks after the 2-dose primary series, through hemagglutination inhibition (HI), single radial hemolysis (SRH), and microneutralization. Local and systemic reactions were recorded. RESULTS: A total of 335 subjects received the H5N1 vaccine, and 137 subjects received the seasonal vaccine. Rates of seroprotection (HI titer of_40) against the H5N1 vaccine antigen were 97% for children 6 to 36 months and 3 to 9 years of age and 89% for older children. All subjects seroconverted in the SRH assay. Microneutralization titers of _40 were achieved by 99% of subjects, and _98% of subjects, respectively. Local reactions, particularly injection site pain in older children, were common, generally mild to moderate in nature, and transient and resolved spontaneously. Up to 5% of participants. There were no vaccine-related serious adverse events in either group. CONCLUSIONS: In this pediatric population, MF59-adjuvanted H5N1vaccine was highly immunogenic, had a good safety profile, reactogenicity comparable with that of an adjuvanted seasonal influenza control vaccine. Pediatrics 2010;126:e762–e770