(Adds expert's comments)
By Ben Hirschler and Julie Steenhuysen
LONDON/CHICAGO, June 23 (Reuters) - U.S. health officialshave advised doctors not to use AstraZeneca's FluMist inthe upcoming flu season based on three years of U.S. datashowing that the nasal spray vaccine is not effective atpreventing influenza.
The decision, announced late Wednesday, was based on areview by the Advisory Committee on Immunization Practices(ACIP) - a panel of experts that advises the U.S. Centers forDisease Control and Prevention - showing the vaccine did notoffer adequate protection.
As a result of the move, the CDC said it will be workingwith manufacturers throughout the summer to ensure there isenough alternative vaccine supply.
AstraZeneca said it would take an $80 million writedown onstocks of its FluMist Quadrivalent vaccine as a result of thedecision. The loss of the vaccine may be a problem for somepediatric practices that have already ordered supplies for theupcoming flu season.
FluMist is currently the only licensed flu vaccine that doesnot require a shot, making it a favored choice by parents ofyoung children.
In the past year, among children aged 2 to 17, FluMist wasonly 3 percent effective, meaning it offered "no protectivebenefit," the CDC said. That compared with conventional flushots, which were 63 percent effective against any flu virusamong children in this age group.
"Unfortunately, and for inexplicable reasons scientifically,the nasal spray vaccine has performed very, very poorly," saidDr. William Schaffner, an infectious disease expert fromVanderbilt University Medical Center, who attended the advisorymeeting.
"ACIP decided it could not in good conscience recommend theuse of this vaccine until the problem had been resolved and newdata had been presented," Schaffner said.
AstraZeneca said the CDC data contrasted with its ownstudies as well as preliminary independent findings by publichealth authorities in other countries suggesting the vaccine was46 to 58 percent effective overall against flu strains duringthe 2015-2016 season.
Schaffner said differences in the performance of the vaccineseen in the United States and other countries were puzzling. Hesaid it may have something to do with the H1N1 component of thevaccine - the strain of flu that cased a pandemic in 2009 - orit may be related to the fact that U.S. children are more likelyto be vaccinated for flu than children in Europe and elsewhere.
Since 2010, the United States has recommended annual flushots for everyone aged 6 months and older. Young children andolder adults are at the greatest risk for serious complicationsof flu, which kills between 3,000 and 50,000 people each year.
AstraZeneca said U.S. sales of FluMist in 2015 totaled $206million, or just under 1 percent of group revenue.
The CDC said FluMist made up about 8 percent of the totalprojected supply of 176 million doses of flu vaccine for theupcoming flu season, and it comprised a third of all flu vaccinegiven to children aged 2 to 17.
Schaffner said it was not clear whether practices that hadordered FluMist would get rebates, and many would have to'hustle" to find vaccine. "There will be turmoil, confusion andgrumpiness generally," he said.
The British drugmaker said it was working with the CDC tobetter understand its data and to make sure U.S. patients canreceive the vaccine in future flu seasons.
In other countries, distribution and use of the vaccine "areprogressing as planned," the company said in a statement.
Despite the setback, AstraZeneca said it maintained its 2016financial outlook of a low-to-mid single digit decline inrevenue and core earnings, at constant exchange rates.
Deutsche Bank analyst Richard Parkes said the U.S. vaccineproblem would likely drag down consensus earnings forecasts forthe current year by around 2 percent and there was a 1-2 percentrisk to future forecasts, if the issue was not resolved.
Shares in AstraZeneca gained 0.3 percent while the Europeandrugs sector rose 0.4 percent.
(Reporting by Ben Hirschler and Julie Steenhuysen; Editing byMarguerita Choy and Andrew Hay)
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