Flu shot doesn't prevent kids' asthma flare-ups

It's recommended that children with asthma get an annual flu shot, but a new report indicates that this does not prevent asthma exacerbations. In fact, there's a hint that influenza vaccination might make asthma worse.

Although recommended in official guidelines, there is no clinical evidence that annual influenza vaccinations reduce the frequency of asthma attacks in children, Dr. Cynthia Christy, of Rochester General Hospital, in New York, and colleagues note in the August issue of the Archives of Disease in Childhood.

In a look-back study, the researchers evaluated 800 asthmatic children of whom half were given a flu shot while the other half were not. The team looked at asthma-related clinic visits, emergency department (ED) visits, and hospitalizations.

After accounting for the severity of asthma, previous use of health services, smoking exposure, and demographic variables, the team found "the vaccine group had a significantly increased risk of asthma-related clinical visits and ED visits"

The researchers found this finding "surprising" and looked for explanations. For example, it could be that children with especially severe asthma were more likely to get a flu shot, in which case " the vaccine group might do worse for that reason."

However, that and other possible reasons did not account for the greater use of asthma-related health services by vaccinated kids.

"While this disturbing result does not show harm from the influenza vaccine, it is suggestive enough to warrant future study," Christy and her colleagues conclude. "It appears that a long term, prospective controlled trial may be needed."

SOURCE: Archives of Disease in Childhood, August 2004.