A new version of the nasal spray vaccine FluMist is better at preventing influenza than traditional flu shots in older babies and children, according to a study sponsored by its maker,
The spray also dramatically reduced the risk of flu-related ear and lower respiratory tract infections, said the report being published in today's New England Journal of Medicine.
But for infants age s 6 to 12 months or older children who sometimes wheeze, shots are safer, the researchers found.
Results of the worldwide test on 8,400 preschoolers, conducted during the 2004-2005 flu season, are being released as health officials encourage flu vaccinations for those 6 months to 5 years old to prevent the spread of the virus.
Robert Belshe of the Saint Louis University School of Medicine and colleagues found that both the spray, which uses live but weakened viruses, and the shots, which contain killed viruses, reduced children's flu rate. But about half as many of those who got nasal spray became ill as those who received flu shots. While 8.6 percent of children getting injections developed flu, the rate was 3.9 percent for those given the spray.
Influenza kills an average of 36,000 Americans every year and up to 500,000 people globally. While most victims are elderly, more than 100 US children, many of them previously healthy, can die in an average flu season.
FluMist is squirted up the nose using a special device. "The big difference is the induction of antibodies in the nose, which is important because this is where the flu virus usually enters the body. The nasal spray flu vaccine appears to induce a more complete immune response," Belshe said.
But the spray may carry special risks for recipients younger than a year.
Those babies were more likely to develop wheezing and 2.3 times more likely to be hospitalized if they received FluMist instead of the shots.
The study used a new version of FluMist that needs only to be refrigerated, not frozen. US regulators approved it last month for healthy children and adults, ages 5 to 49.
MedImmune hopes to expand its market by showing that the spray is safe and effective for preschoolers. The US Food and Drug Administration is expected to rule on that question by June.