The flu vaccine reduced children's risk of developing a life-threatening influenza infection by three quarters during the 2010-2011 and 2011-2012 flu seasons in the United States, according to a new report from the Centers for Disease Control and Prevention.
Although vaccination may not always prevent the flu, the new findings suggest flu shots do protect kids from the more serious complications of infection that require hospitalization, CDC officials said.
"These study results underscore the importance of an annual flu vaccination, which can keep your child from ending up in the intensive care unit," Dr. Alicia Fry, a medical officer in CDC's Influenza Division, said in a statement. "It is extremely important that all children — especially children at high risk of flu complications — are protected from what can be a life-threatening illness." [5 Dangerous Vaccination Myths]
Fry's team studied 216 children ages 6 months to 17 years old who were admitted to 21 different pediatric intensive care units in the United States during the 2010-2011 and 2011-2012 flu seasons, looking to see which kids had been vaccinated. Of the children in the study, 44 tested positive for influenza, and 172 were influenza-negative controls. The researchers also looked at 93 kids who had not been hospitalized during those flu seasons, as "community controls."
Flu vaccination reduced a child's risk of landing in the ICU for flu by 74 percent, the researchers found.
More than half (55 percent) of the kids who came down with life-threatening case of the flu had at least one underlying chronic medical condition that placed them at higher risk of complications, CDC officials said. Still, the study revealed low vaccination rates among the kids hospitalized for the flu — only 18 percent of them had been fully vaccinated against influenza. In contrast, 39 percent of the ICU controls and 51 percent of community controls had received flu shots.
Previous studies have suggested that adults who get the flu develop less severe symptoms if they were vaccinated. A study published last year in the journal Clinical Infectious Diseases found that adults of all ages who got the flu shot were less likely to be hospitalized with the flu.
The CDC recommends seasonal flu shots for everyone 6 months of age and older. A new flu vaccine is concocted each year, as strains of the virus are constantly changing.
Health officials typically measure the effectiveness of a vaccine based how well it protects against visits to the doctor for flu symptoms, which can include fever, cough, sore throat, runny nose, muscle aches, headaches and sometimes diarrhea and vomiting. By this standard, the effectiveness of the 2010-2011 flu shot was 60 percent; for the 2011-2012 vaccine, it was 47 percent, CDC officials said.
The new findings were detailed Thursday (March 27) in the Journal of Infectious Diseases.
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