nasal-spray flu vaccine appears safe and effective for young children but caution should be noted for potential respiratory risks, according to a newly issued government report.
The staff of the Food and Drug Administration issued the findings Monday, two days before a group of medical advisors vote on MedImmune's request to expand its FluMist vaccine to children 12 months to 59 months who don't have respiratory problems such as wheezing or asthma. FluMist is now prescribed to healthy people between the ages of 60 months to 49 years.
The FDA isn't required to follow the recommendations of its outside advisors, but it usually does so. FDA staff reports are routinely issued before advisory panels meet.
A Slow Start
FluMist was approved by the FDA four years ago, in time for the 2003-04 flu season. But the vaccine has been a major disappointment, partly because it doesn't cover the very young or the very old. The federal Centers for Disease Control and Prevention says people 65 years and older as well as children two years and younger are the most likely to be hospitalized by the flu.
FluMist also has been a failure because managed care firms balked at its higher price vs. flu shots and because storage requirements caused inconvenience for pharmacists and doctors.
In January, MedImmune won
FDA approval for a more convenient version, called CAIV-T. The original FluMist had to be frozen before being used; the new version needs only to be kept in a refrigerator.
Monday's FDA staff report says that although there are more "wheezing events" with children receiving CAIV-T vs. those receiving traditional shots, the difference between the groups is small.
"Our interpretation is that the data do not suggest a clinically significant safety signal for wheezing," the report says. The difference in wheezing is most notable for children under 24 months.
The FDA staff says medical advisors must weigh these side effects in assessing the risks and benefits of FluMist vs. injectable vaccines.
The advisory committee vote takes on an extra dimension due to
$15.6 billion takeover bid for MedImmune. FluMist provided only $36 million of MedImmune's $1.28 billion in revenue last year. AstraZeneca had revenue of $26.5 billion; and the question is how much patience will it have for a tiny product?
MedImmune says its research shows FluMist
did a better job than a flu shot in young children. Traditional shots contain an inactivated virus; FluMist has a weakened, live virus.
The research, published earlier this year in the
New England Journal of Medicine
, says FluMist "should be a highly effective, safe vaccine for children 12 to 59 months of age who do not have a history of asthma or wheezing."
Among existing flu vaccines, Fluzone from
can be prescribed for children as young as six months while
Fluvirin can be given to children as young as 4 years.
A Supply-Demand Issue
Even if MedImmune wins expanded use for FluMist, a spokesman said the company won't make any more than the seven million doses it has planned for the upcoming flu season. That means MedImmune will still be a small player because the CDC recently predicted there will be a record number of doses -- as many as 132 million.
The biggest providers are Sanofi-Aventis, Novartis and
. The number could go higher if Australia's
gets permission to sell its flu vaccine.
If people paid attention to public health experts, there would be plenty of demand for flu shots. The CDC wants 218 million Americans vaccinated for the upcoming flu season, saying this figure represents people at highest risk -- those 50 years old and over, children under five years old, health-care workers, pregnant women and people with chronic diseases.
But Americans have never paid much attention to the experts, and vaccine-makers have never made enough product to meet experts' recommendations.
The 2006-07 flu season produced a record number of doses -- 120.9 million -- but the CDC says only 102.5 million were distributed and another 1 million was stockpiled. However, "distributed" isn't the same as "injected." An agency spokesman said the CDC doesn't know how much of the supply was used. Because the flu strains change yearly, all unused vaccine must be destroyed each June 30.
Excluding the 2006-07 season, manufacturers have produced less than 100 million doses per year and have distributed no more than 83.1 million in recent years. The worst was the 2004-05 season when
cancelled all distribution. Only 61 million doses were available for 2004-2005, and 4.5 million doses went unused.