Evaluation of bivalent live attenuated influenza A vaccines in children 2 months to 3 years of age: safety, immunogenicity and dose-response

Abstract

1126 children, 2 months to 3 years old, received a single intranasal dose of 10(4), 10(6), or 10(7) TCID50 of cold adapted (ca) A/Kawasaki/9/86 (H1N1) and A/Beijing/352/89 (H3N2) or placebo, in a double blind, placebo-controlled, safety and immunogenicity trial. No reactogenicity attributable to vaccine was demonstrated. A single bivalent 10(6) or 10(7) dose produced high rates of seroconversion to H1N1 (77%) and H3N2 (92%) in seronegative children > 6 months old; serologic responses were lower to H1N1 (P < 0.001) and H3N2 (P = 0.01) in younger infants. A single 10(6) dose of bivalent ca influenza A vaccine can be immunogenic in children, but response is age dependent.