Analysis: Flu hits more kids

BOSTON, July 7 (UPI) -- This October Dr. Katherine Poehling of Nashville will call her children's pediatrician and ask when the new influenza vaccine is going to be available.

She'll make the appointment to have her young children, herself and the rest of her household vaccinated against whatever form of influenza shows for the 2006-2007 season.

"Honestly, preventing infection with the influenza virus is far better than being able to diagnose it or treat it," she told United Press International.

Poehling authored a study published in this week's New England Journal of Medicine that reports that influenza among young children is far more prevalent than previously believed.

For every child hospitalized with influenza, Poehling said that as many as 250 others are treated for acute infections at their primary care or pediatric physicians' offices or as outpatients in the emergency departments of hospitals.

Poehling and colleagues working with the New Vaccine Surveillance Network identified children from clinics and hospitals in Davidson County (Nashville), Tennessee; Hamilton County (Cincinnati), Ohio, and Monroe County (Rochester), New York and estimated the impact of influenza infections in the 2002-2003 season and the 2003-2004 season.

The researchers determined that about one child out of every 1,000 children was hospitalized with influenza infection, yet during the 2003-2003 influenza season about 50 children out of 1,000 were taken to doctors clinics and 6 per 1,000 were seen in emergency rooms. During the 2003-2004 influenza season there were 95 per 1,000 clinic visits and 27 per 1,000 emergency department visits.

"Among young children, outpatient visits associated with influenza were 10 to 250 times as common as hospitalizations," Poehling said. "Few influenza infections were recognized clinically." The researchers found that only about 28 percent of infections treated in hospital and just 17 percent treated in the outpatient setting were correctly identified as influenza. In general, however, Poehling told UPI that clinicians assumed the infections were of a viral nature.

The study results, she said, had been presented to the Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices in February. With indication of a greater prevalence of influenza, that committee has urged that children between the ages of 6 months and 5 years be vaccinated against influenza each year, Poehling said. Previously the recommendation was to vaccinate children between 6 months and 2 years of age.

The influenza season in the United States typically begins in November and lasts for three to four months. Sometimes the season does not begin until January, she said. "No one really knows why influenza peaks in the winter months," she said. "There are a great number of theories but it still remains a medical mystery."

She said that vaccination against the 2006-2007 influenza does not mean a person will have protection against the following season's virus. "Sometimes vaccination will be somewhat protective if the viruses are very similar year to year," Poehling said, "but you are just lucky if one vaccine protects against the new bug.

"The hard part is getting parents to get their children vaccinated each year."

The report by Poehling and the New Vaccine Surveillance Network, while showing a greater impact of influenza than was previously considered, may still be conservative, said W. Paul Glezen, professor of molecular virology and microbiology at Baylor College of Medicine in Houston.

He suggested that the report may have only captured data from children whose parents carried medical insurance. He said that because those without insurance tended to be at lower socioeconomic levels there was likelihood that these children might suffer greater prevalence of infection.

"It is clear that influenza causes more deaths and hospitalizations than all other diseases that are preventable by vaccine combined and universal immunization against influenza should be considered," Glezen said in an editorial that accompanied Poehling's report in the journal.

He also said the work of the surveillance groups could not only stem the outbreak of seasonal influenza but may help contain any major pandemic that emerges.