GlaxoSmithKline's Pandemrix vaccine, which was a split virus vaccine incorporating an adjuvant, produced a greater immune response than Baxter's Celvapan vaccine.
Pandemrix also had high sero-conversion rates in children aged less than three years, but led to more reactions in children, Dr Claire Waddington and colleagues from Oxford University's Department of Paediatrics found.
Writing in the BMJ, the researchers commented: 'These data provide important information to guide immunisation policy in an influenza pandemic and indicate the potential for improved immunogenicity of seasonal influenza vaccines in children.'
A spokeswoman for Pandemrix manufacturer GSK said initial reports on the epidemiology of the swine flu pandemic had shown that the virus had a greater impact on children as compared with the impact of seasonal influenza.
'Therefore,' she said, 'even though (the vaccine is) more reactogenic, providing a vaccine that stimulated a greater immune response may have an added benefit for this population.