FDA Panel Rejects Inhaled Flu Vaccine

July 27, 2001 (Washington) -- A new vaccine that backers say will stop the flu without requiring a shot was given a mixed recommendation from an advisory committee to the Food and Drug Administration.

Initially, the panel praised the product, called FluMist, for its effectiveness in preventing flu, particularly in adults. But ultimately, the advisors balked at FluMist's safety, saying the data were inadequate.

Among the concerns: the possibility the vaccine -- made from a weakened strain of a live flu virus -- could cause pneumonia, asthma, or spread the disease to others.

Panel chairman Robert Daum, MD, from the University of Chicago Children's Hospital, noted the progress toward an inhaled vaccine was "marvelous" but said it was still a "work in progress." The FDA reviewers conceded they hadn't had an opportunity to fully review the data on FluMist. Still, studies show the vaccine is up to 94% effective in preventing the flu.

Severe fever, one of the disease's worst side effects, was diminished by 25%. "It's not a paltry reduction," said Kristin Nichol, MD, MPH, of the VA Medical Center in Minneapolis.

Boyd Clark, president and CEO of drugmaker Aviron, based in Mountain View, Calif., said he was disappointed by the panel's action but remained optimistic about getting FluMist licensed by its original target date of the 2002-2003 flu season. "We will get the product over the line," says Clark.

FluMist is given to patients using a small syringe. The dose, twice yearly for children, once yearly for adults, is squirted painlessly into each nostril. FluMist uses a totally different approach than the current "killed virus" version. It has been engineered to cause a mild infection in the nose, where it's relatively cool, but doesn't travel down to lungs where it would cause the flu.

Backers say it's unlikely to make you sick.

"The hopes are that the vaccine will be more cross protective, provide a longer immunity, and stimulate additional components of the immune system that the current inactivated vaccine doesn't do ... and elicit a longer immune response," says Linda Lambert, PhD, influenza program officer at the National Institute of Allergy and Infectious Diseases.

Aviron is seeking approval for healthy people aged 1-64 years. That would be a potential 150 million users. Flu is a devastating illness, causing an estimated 20,000 deaths annually in the U.S. and 50 million infections.

Just one-third of healthy adults are currently vaccinated, since the vaccine is only recommended for high-risk groups.

Public health officials have long sought a better way of protecting people from the flu, which is increasing in children at four times the rate of other age groups. The federal government has sunk millions into this so-called "cold adapted" approach.

Even though the vaccine has been in development for some 40 years and given to 24,000 patients in studies, most of them children in a Northern California HMO, the FDA panel had concerns.

Daum, who said he'd like another chance to review the new vaccine, worried about the risk for a flu-like illness after vaccination, as well as the effects of children getting a dose of live flu vaccine year after year.

The panel voted 8 to 7 that the vaccine is effective in children, and 12 to 2 that it works in adults. However, on the vital safety issue, the panel said no by a margin of 10 to 4.

The FDA usually, but not always, follows the recommendations of its advisory committees.