November 20, 2012
(USA TODAY) -- When it comes to flu vaccines, most kids clearly and loudly prefer the nasal spray, at least compared with the traditional shot in the arm.
As it turns out, those instincts are right on the nose.
With mounting evidence that the nasal spray FluMist works much better in kids than an injection, experts are considering whether the Centers for Disease Control and Prevention actually should steer children toward the less painful alternative.
The debate reflects a growing sense among experts that people of different ages may get better protection from different types of vaccines, says Gregory Poland, a professor at the Mayo Clinic in Minnesota and an adviser to the CDC. The CDC now issues only general recommendations for the flu. The agency recommends that everyone over age 6 months get an annual flu vaccine, but it does not specify which kind.
An influenza work group, part of the CDC's Advisory Committee on Immunization Practices, is considering whether the CDC should begin tailoring those recommendations by expressing a preference for FluMist in healthy children ages 2 to 8, says Poland, a group member.
"We've treated all flu vaccines the same, but they are not," says Arnold Monto, a professor at the University of Michigan School of Public Health. "We're moving away from a one-size-fits-all flu vaccine."
Canada and the United Kingdom already express a preference for nasal spray vaccines for children.
A person's immune system changes with age, says Robert Belshe, director of the vaccine center at St. Louis University. In a study published in The New England Journal of Medicine, Belshe found that kids who got FluMist were half as likely to get influenza as those given an injection.
FluMist offered broader protection than the shot, even when the strain of virus in circulation wasn't a good match to the strain used in the vaccine, his study found.
In that study, about 5% of children vaccinated with FluMist came down with influenza compared with 10% of those given an injection.
Not all children can get FluMist, Belshe says. Though injectable vaccines are approved for those over 6 months old, FluMist isn't recommended for children with asthma or babies under 2 because of a slightly increased risk of wheezing.
Younger children seem to respond better than older kids and adults to FluMist, which uses a live but weakened virus that can't cause influenza, Belshe says. FluMist doesn't cause the flu because the viruses are specially engineered to grow only at the relatively cool temperatures of the nose. The viruses in FluMist can't reproduce in the lungs, which are a degree or two warmer, says Chris Ambrose, vice president for medical and scientific affairs at MedImmune, which makes FluMist.
Because children haven't had much exposure to the flu, their immune systems respond vigorously to live viruses, Belshe says. The CDC says FluMist can reduce infections by up to 92%. Adults ages 18 to 49 seem to respond better to the injection, which contains a dead virus that also can't cause influenza, Monto says.
Adults over 65 have weaker immune systems and don't respond well to any flu vaccine, and they are among the most vulnerable to flu complications, Belshe says. The Food and Drug Administration has approved a high-dose flu shot for seniors that seems better at stimulating the immune system. But definitive studies to show whether the vaccine substantially reduces flu infections are still in the works, Belshe says.
Copyright 2012 USA TODAY, a division of Gannett Co. Inc.