Both vaccines were well tolerated. The split virus vaccine was more immunogenic and achieved higher seroconversion rates than the whole virus vaccine, especially in children aged less than 3 years. The split virus vaccine was also associated with more reactions compared with the whole virus vaccine, although these reactions were generally in keeping with the product data produced by the manufacturer. Significantly fewer reactions, including fever, were observed after a first dose of adjuvanted vaccine than a second, especially in younger children.

The authors conclude: "In this first direct comparison of an AS03B adjuvanted split virion versus whole virion non-adjuvanted H1N1 vaccine, the adjuvanted vaccine, while more reactogenic, was more immunogenic and, importantly, achieved high seroconversion rates in children aged less than 3 years. This indicates the potential for improved immunogenicity of influenza vaccines in this age group."

Source: BMJ-British Medical Journal