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No clear evidence that antivirals prevent complications in children with seasonal flu

(Research: Neuraminidase inhibitors for treatment and prophylaxis of influenza in children: systematic review and meta-analysis of randomised controlled trials)

LONDON, Aug. 13, 2009 --The antivirals oseltamivir (Tamiflu) and zanamivir (Relenza) are unlikely to prevent complications in children who have seasonal flu, according to research published on today.

The authors say that it is difficult to know the extent to which their findings can be generalised to children in the current swine flu pandemic but, based on current evidence, the effects of antivirals on reducing the course of illness or preventing complications might be limited.

While the study shows that antivirals shorten the duration of flu in children by up to a day and a half, it also shows that they have little or no effect on asthma flare-ups, increased ear infections or the likelihood of children needing antibiotics. The antiviral Tamiflu is also linked to an increased risk of vomiting.

The authors, led by Dr Matthew Thompson from the University of Oxford, add that the study reveals the effectiveness of using antivirals to contain the spread of flu. They conclude that 13 people need to be treated to prevent one additional case; therefore antivirals reduce transmission by 8%.

During seasonal flu epidemics children are at high risk, with over 4 in 10 (40%) preschool children getting the virus and 3 in 10 (30%) school age children doing so. School age children are also the main source of spread of flu into households, say the authors.

The main strategy to control flu is vaccination but coverage can be low and often there is not enough time to produce and distribute vaccines in response to emerging strains. Therefore current control strategies include using antiviral medications to prevent the virus spreading as well as treating infected individuals.

Thompson and his colleagues say the last review of this strategy was carried out in 2005 and a more up to date assessment of the benefits and harms of this treatment was now required in the light of widespread use of these drugs during the current swine flu pandemic.

So they carried out a review of four trials on the treatment of flu in 1,766 children (1,243 with confirmed flu, 55 to 69% with type A, the same strain as swine flu) and three trials involving the use of antiviral to limit the spread of flu.

"While morbidity and mortality in the current pandemic remain low, a more conservative strategy might be considered prudent, given the limited data, side effects such as vomiting, and the potential for developing resistant strains of influenza," they say.

Dr Matthew Thompson, Senior Clinical Scientist, Department of Primary Health Care, University of Oxford, UK

Dr Carl Heneghan, Deputy Director CEBM & Clinical Lecturer, DPHC, University of Oxford, UK

Posted: August 2009