Annual flu shot cuts need for doctors'
visits, hospitalization among children
BOSTON - September 4, 2007 - Children under the age of 5
who receive an annual flu shot have a greatly reduced risk of needing
to see their doctor or be admitted to the hospital because of flu-related
illness. A new study in the September issue of Pediatrics
that analyzes how many outpatient visits or hospitalizations might
be prevented by childhood influenza immunization finds that vaccinating
only half U.S. children could eliminate as many as 650,000 doctor's
office visits and 2,250 hospitalizations in a year.
"We found that only 12 to 42 children need to be vaccinated
to directly prevent one outpatient visit for the flu," says
Elizabeth Lewis, MD, the study's first author. "And since the
vaccination of some children in a preschool or daycare setting also
reduces the chance that unvaccinated children would be exposed to
the flu virus, the effects of vaccination are probably even greater
than we found." Lewis, now with MassGeneral
Hospital for Children, worked on the study while at Vanderbilt
University Medical School.
The American Academy of Pediatrics recommends that all children
between the ages of 6 months and 5 years receive an annual flu shot.
Since the specific virus responsible for the flu varies from year
to year, determining the preventive impact of influenza vaccination
of children has been challenging. For the current study, the authors
analyzed existing data from several sources reporting on flu-related
outpatient visits or hospitalizations covering several flu seasons.
These included years in which the flu season was relatively mild
and well as those in which flu was widespread and caused more serious
Each year's flu vaccine needs to be designed in advance, based
on which strains of virus are anticipated to be prevalent in the
coming year. Because the accuracy of that prediction varies, the
effectiveness of the flu vaccine also varies from year to year.
To account for that variation, the research team calculated results
based on several potential rates of vaccine efficacy.
"Even in years when only half the immunized children are well
protected against flu, vaccination can make a real difference,"
Lewis says. "I'd advise parents to have their children vaccinated
to protect their own health, the health of grandparents and other
family members, and the health of other children they are around."
The co-authors of the Pediatrics report are principal investigator
Katherine Poehling, MD, MPH, now at Wake Forest University School
of Medicine; Marie R. Griffin, MD, MPH, Kathryn M. Edwards, MD,
Yuwei Zhu, MD, MS, of Vanderbilt University Medical Center; and
Peter G. Szilagyi, MD, MPH, University of Rochester School of Medicine
and Dentistry. The study was funded by the Robert Wood Johnson Foundation
and the National Institutes of Health.
Massachusetts General Hospital, established in 1811, is the original
and largest teaching hospital of Harvard Medical School. The MGH
conducts the largest hospital-based research program in the United
States, with an annual research budget of nearly $500 million and
major research centers in AIDS, cardiovascular research, cancer,
computational and integrative biology, cutaneous biology, human
genetics, medical imaging, neurodegenerative disorders, regenerative
medicine, systems biology, transplantation biology and photomedicine.
MGH and Brigham and Women's Hospital are founding members of Partners
HealthCare HealthCare System, a Boston-based integrated health care
Media Contacts: Valerie
Wencis, MGH Public Affairs
MGH Public Affairs
Physician Referral Service: 1-800-388-4644
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