Use of the influenza vaccine was not associated with preventing hospitalizations or reducing physician visits for the flu in children age five and younger during two recent seasons, say scientists.

As of June 2006, US health officials recommend annual vaccinations for all children age 6 to 59 months. “An inherent assumption of expanded vaccination recommendations is that the vaccine is efficacious in preventing clinical influenza disease,” the authors write. 

Peter G. Szilagyi, MD, MPH and colleagues studied 414 children age five and younger who developed influenza during the 2003-2004 or 2004-2005 seasons. Their vaccination status was compared with that of more than 5,000 children from the same three counties who did not have influenza during those seasons. 

A suboptimal match between the strain of influenza in the vaccine and that circulating in the public during those two seasons may have contributed to the poor effectiveness, the authors note. 

This study comparing cases with controls adds important information about vaccine effectiveness in children but should be combined with additional research, including studies of years with good vaccine match, they conclude. “Further studies of influenza vaccine effectiveness are needed using a variety of study designs (that adjust for confounders) to assess the yearly impact of influenza vaccination programs for children, particularly as higher rates of vaccination are achieved in the study population,” the authors write.  

APAM – October 2008;162:943-51.

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