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| | | ![]() Flu Vaccine Not Associated With Reduced Hospitalisations or Outpatient Visits Among Young Children CHICAGO -- October 6, 2008 -- Use of the influenza vaccine was not associated with preventing hospitalisations or reducing physician visits for the flu in children aged 5 years and younger during 2 recent seasons, perhaps because the strains of virus in the vaccine did not match circulating strains, according to a study in the October issue of the Archives of Pediatrics & Adolescent Medicine. Peter G. Szilagyi, MD, University of Rochester School of Medicine and Dentistry and Strong Memorial Hospital, Rochester, New York, and colleagues studied 414 children aged 5 years 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 3 counties who did not have influenza during those seasons. Before the researchers considered any other factors, children with influenza appeared to have lower vaccination rates than children without influenza. "However, significant influenza vaccine effectiveness could not be demonstrated for any season, age, or setting after adjusting for county, sex, insurance, chronic conditions recommended for influenza vaccination, and timing of influenza," the authors wrote. A suboptimal match between the strain of influenza in the vaccine and that circulating in the public during those 2 seasons may have contributed to the poor effectiveness, the authors noted. In the 2003-2004 season, 99% of circulating influenza strains were caused by the influenza A virus, but only 11% of influenza A strains across the United States were similar to those in the vaccine. "The 2004-2005 season was less severe and the vaccine was a better match to circulating strains than in 2003-2004, but still only 36% of virus isolates were antigenically similar to vaccine strains," they wrote. "Further studies of influenza vaccine effectiveness are needed using a variety of study designs to assess the yearly impact of influenza vaccination programs for children, particularly as higher rates of vaccination are achieved in the study population." SOURCE: Archives of Pediatrics & Adolescent Medicine
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