It's recommended that children with asthma should get an annual flu shot. A recent study indicates that this does not prevent asthma exacerbations. In fact, there's a hint that influenza vaccination might make asthma worse. Researchers from the Rochester General Hospital, in New York found that there is no clinical evidence that annual influenza vaccinations reduce the frequency of asthma attacks in children. 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 hospitalisations. 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 In search for explanations researchers found that 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.
Archives of Disease in Childhood,
June 2004