Dr Avni Joshi and his team studied 236 children with influenza evaluated at the Mayo Clinic in Minnesota over a six-year period.
The researchers found that children given the trivalent inactivated flu vaccine were 2.97 times more likely to be admitted to hospital for flu than those who had not been vaccinated.
The study set out to assess the effectiveness of the trivalent inactivated flu vaccine in asthmatic children, on the basis that exacerbations of asthma are known to be associated with influenza.
Overall, a trend towards higher rates of hospital admission for flu was found, both for asthmatic and non-asthmatic children who had been vaccinated.
Dr Joshi, who presented the findings at the American Thoracic Society's annual conference this week, stressed that the findings do not implicate the flu vaccine as a cause of the hospital admissions.
'More studies are needed to assess not only the immunogenicity but also the efficacy of different influenza vaccines in asthmatic subjects,' Dr Joshi said.
- American Thoracic Society conference 2009
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