Aviron's nasal flu vaccine turned down by FDA panel

A US Food and Drug Administration advisory committee has turned down bya vote of 10 to four an application by Aviron to market FluMist, an influenza vaccine delivered by a nasal spray, after concluding that the company had not provided sufficient evidence of the product's safety. The panel's rejection is the latest in a string of delays in the FluMist program, which was originally scheduled to debut in time for the 1999/2000 flu season in the USA, but had its initial license application sent back by the FDA in 1998 (Marketletters passim).

The FDA panel agreed that the efficacy of the vaccine had been demonstrated, but it had concerns about the safety of the live, attenuated flu strain used in the vaccine, particularly when delivered in combination with other immunizations during pediatric vaccine schedules, as well as the risk that children receiving it might go on to develop pneumonia or asthma complications. For example, the agency uncovered 37 cases of pneumonia in FluMist-treated patients in clinical trials, compared to 12 cases in control groups, while some children with asthma received the drug in the studies, even though this was contraindicated in the trial protocols.

In addition, some of the panel members expressed the concern that certain high-risk patients, such as the elderly, may persuade doctors to prescribe the nasal spray vaccine for them rather than the injectable form, even though trials of the FluMist in this population have not been completed.