(RALEIGH) – This year’s flu season is in full swing with 41 states now reporting widespread illness.Unfortunately, not enough children are getting the flu shot even though health officials recommend that all children 6 months and older get the vaccine.  According to a new study by researchers at Wake Forest Baptist Medical Center less than 45 percent of children were vaccinated against the flu during a five-year study period.

“Our research showed that one in six children under age 5 who went to an emergency department or clinic with fever and respiratory symptoms during the peak flu seasons had the flu,” said Katherine Poehling, M.D., associate professor of pediatrics and epidemiology at Wake Forest Baptist and lead author of the study, published in the online edition of the February issue of Pediatrics. “Many of those illnesses could have been prevented by vaccination, the best known protection against the flu.”

The researchers found that children less than 6 months of age had the highest hospitalization rates with flu. “Parents should include a yearly flu shot to protect themselves and their children,” Poehling said. “The best way to protect infants too young to receive the influenza vaccine is for pregnant women, the infant’s family members and contacts to get the shot, too.”

The study, funded by The Centers for Disease Control and Prevention (CDC), reported population-based data on confirmed flu cases in children younger than 5 years old in three counties in Ohio, New York and Tennessee. More than 8,000 children seen in inpatient, emergency department and clinic settings were included during five flu seasons from 2004 through 2009.

During the study period, the researchers found that the overall flu vaccination coverage changed little, whereas the rates of influenza hospitalization and prevalence of influenza among outpatients varied annually. The proportion of infants less than 6 months old diagnosed with flu increased to 48 percent as compared to 28 percent in a previous study (2000 – 2004) conducted by the research team.

However, for children between ages 6 months to 5 years, the proportion diagnosed with the flu remained similar in both studies. These data suggest that doctors’ awareness of the flu among young infants has increased, but hasn’t among older children.

The study also showed that seasonal flu remains an important cause of hospitalization, emergency department and outpatient visits among children and that the use of tools known to reduce flu rates -- vaccination and antiviral medications – were underused, Poehling said.

Additional efforts are needed for greater dissemination and use of the existing recommendation for vaccination of children six months and older and of pregnant women, which partially protects younger infants. Also needed are the development and dissemination of evidence-based guidelines for laboratory testing and therapeutic options, including antiviral medications.

Funding for the study was primarily provided by the U.S. Centers for Disease Control and Prevention. In addition, Poehling received research support from the National Institute of Allergy and Infectious Diseases grant RO1AI079226, and the Wachovia research Fund.

Co-authors are Kathryn Edwards, M.D., Marie Griffin, M.D., and Yuwei Zhu, M.D., of Vanderbilt University Medical Center;  Peter Szilagyi, M.D., Caroline Hall, M.D., Geoffrey Weinberg, M.D., of University of Rochester Schools of Medicine and Dentistry; Mary Staat, M.D., Monica McNeal, M.S., of University of Cincinnati College of Medicine;    Beverly Snively, Ph.D., Cynthia Suerken, M.S., of Wake Forest Baptist;  Sandra C. Chaves, M.D., Carolyn Bridges, M.D., and Marika Iwane, Ph.D., of National Center for Immunization and Respiratory Diseases.