Currently, two doses of influenza vaccine are recommended for children younger than 9 years receiving influenza vaccine for the first time. While the scientific support for 2 doses of vaccine in infants and toddlers is sound, the need for 2 doses of vaccine for adequate immunogenicity in older children is less certain. If the immunogenicity of a one-dose vaccine regimen is comparable to a two-dose regimen, then one dose would be preferable for reasons of safety, practicality and economics, and would reduce a major barrier to vaccination in this injection-adverse age group. This study compared the immunogenicity and reactogenicity of one versus two doses of influenza vaccine in children aged 5 to 8 years old receiving influenza vaccine for the first time. All children enrolled in the study received two doses of vaccine, and the immune response after one dose of vaccine was compared to the immune response after two doses of vaccine.
