A long-awaited painless flu vaccine suffered a setback Friday as government scientists declared there are too many safety questions for Aviron's nasal vaccine to be sold yet.
Advisors to the Food and Drug Administration said FluMist clearly can protect against the flu and probably one day will prove safe enough for certain Americans to use. But unlike today's flu shots, FluMist is made with live influenza virus, so the nation needs more proof that squirting live virus into a person's nose--especially a toddler, who would be a prime target--is safe, panelists concluded.
Concerns include how well FluMist combines with other vaccines that toddlers receive and whether there might be a rare risk of pneumonia or asthma among certain children.
The FDA is not bound by its advisors' recommendations but typically follows them.
Aviron had hoped to begin selling limited supplies of FluMist in time for this year's flu season, offering the first needle-free vaccine alternative to healthy people ages 1 to 64. (Studies of FluMist in the elderly and people with diseases that make them particularly vulnerable to flu complications still are underway.)
Aviron Chief Executive C. Boyd Clarke said the company hopes to answer the panel's questions in time for FluMist to be used in the 2002-2003 flu season.
About 70 million people get flu vaccines, a shot in the arm, each year. Yet influenza still kills 20,000 Americans each year and hospitalizes about 100,000.
FluMist was 93% effective in children 15 months or older, the panelists agreed; about half the advisors said it wasn't proved effective in younger children.
A study with healthy adults didn't prove FluMist cut the incidence of flu-like illnesses but it did lower severe illness by 19%.
Among the concerns cited by the panel were:
* Because a different type of flu strikes every year, people must be vaccinated each year--yet Aviron hasn't studied repeated annual doses.
* FluMist isn't supposed to be given to anyone with asthma. But some asthmatic children did get it during testing anyway, and scientists asked if a handful of subsequent asthma attacks were possibly related to the vaccine.
* No one yet knows if FluMist would work as well as today's flu shots.