A recent study shows a nasal spray vaccine to combat the flu virus is more effective in young children than the needle injection method currently in use.

The study was released Thursday in the New England Journal of Medicine. It said children younger than 5 years old who received the nasal vaccine developed 55 percent fewer cases of the flu than those who received the injected vaccine.

"This vaccine will eventually lead to an easier process of vaccination and will substantially change the way pediatricians vaccinate children against the flu," said Dr. Robert Belshe, lead author of the study and director of the Center for Vaccine Development at Saint Louis University Health Sciences Center.

The nasal spray not only proved better than the injectable vaccine against the strains of influenza actually contained in the vaccines, it also prevented more infections caused by strains that were genetically drifted, or different, from the vaccine strains.

"It's as though you get a double-bang effect," said Dr. William Schaffner, chair of the department of preventive medicine at the Vanderbilt Medical School in Nashville, Tenn. "You get protection against the kind of influenza that is in the vaccine, as well as the kind that sometimes occurs out in the community and is a little bit different."

There are some drawbacks to the new vaccine. Children who are 6 months to 1 year of age were almost twice as likely to develop wheezing and other illnesses within six weeks of their immunization if they received the nasal vaccine rather than the injected one.

In addition, all children with a history of wheezing or asthma -- even older children -- were slightly more likely to be hospitalized if they were given the nasal vaccine.

The reason for the rise in other illnesses is unclear, but it is concerning enough that Belshe says, "The nasal spray vaccine should become the vaccine of choice for children over 1 year of age without a history of wheezing [or asthma]. It is easier to use and has greater efficacy."

The nasal vaccine, which is marketed under the name FluMist, is currently approved by the Food and Drug Administration for use only in people between 5 and 49 years old. The manufacturer has already submitted application data to the FDA, and approval for the use of FluMist in children under 5 years of age will hopefully occur in time for the next flu season.