Pre-schoolers drive spread of flu virus

NEW YORK - Otherwise healthy preschool-age children drive the spread of influenza in the community, a finding that could have major implications for immunisation policy, investigators contend.

"What we found was quite striking," Dr John Brownstein from Children's Hospital Boston said.

In all six healthcare settings monitored - including ambulatory care sites and emergency departments - "three- and four-year-olds were consistently the first age to get infected with influenza".

This age group developed influenza-like illnesses as early as late September, while younger children showed up one or two weeks later, followed by older children in October and adults in November (for the Northern Hemisphere winter).

The findings, based on influenza surveillance data spanning four recent flu seasons for the greater Boston area, are reported in the American Journal of Epidemiology.

Current immunisation policies in the US recommend universal influenza vaccination for the elderly and for children six to 23 months of age.

Influenza vaccination is currently advised for children two years of age or older only if they have high-risk medical conditions.

Dr Kenneth D. Mandl, also from Children's Hospital Boston and co-author of the report, said that "on the one hand, it is not surprising that preschoolers are bringing home infections into the family".

"There is ample medical literature to show that young kids do spread influenza throughout households and vaccinating them will reduce household spread."

What's new about their study, he noted, "is that it shows that these kids seem to be having a very large impact on the community-wide spread of influenza starting right at the beginning of each year's influenza epidemic.

"What we didn't know before is that three- to four-year-olds seem to spark the whole epidemic."

Flu vaccination in NZ

* Flu vaccination is recommended for everyone.

* Free vaccination is offered to people aged 65 and over and to adults and children with certain chronic conditions such as heart disease, diabetes and severe asthma.

- REUTERS