Flumist Vaccine Seen Safe in Post-approval Review

NEW YORK (Reuters Health) - The safety of Flumist, the influenza vaccine that's administered as a nasal spray, was shown in testing before it was approved for sale, and now its safety has been confirmed in an analysis of adverse events over the first two seasons of use.

In June 2003, the US Food and Drug Administration approved the live, attenuated flu vaccine for intranasal administration in healthy persons between 5 and 49 years of age. Although pre-approval testing suggested that the vaccine is safe, the trials were not large enough to reliably assess the risk of rare side effects.

In the present study, Dr. Hector S. Izurieta, from the FDA in Rockville, Maryland, and colleagues analyzed data reported to the US Vaccine Adverse Event Reporting System (VAERS) during the 2003-2004 and the 2004-2005 flu seasons. The researchers' findings appear in this week's Journal of the American Medical Association.

Roughly, 2.5 million people were given Flumist during the study periods, the report indicates. A total of 460 adverse event reports were logged from August 2003 through July 2005, including 73 reports (16 percent) involving individuals who should not have received the vaccine in the first place.

None of the adverse events proved fatal, but there were some serious side effects nonetheless. Possible anaphylaxis -- a severe allergic reaction -- was noted in seven reports; the numbness disorder called Guillain-Barre syndrome in two; Bell palsy -- which involves facial nerves -- in one; and asthma exacerbations in eight.

"Reports to VAERS in the first two seasons of (Flumist) use did not identify any unexpected serious risks with this vaccine when used according to approved indications," the investigators state.

However, they continue, "The finding of a high proportion of vaccine administration errors and the reports of use among persons for whom this vaccine was not indicated underscore the need for the clinician to follow the package insert indications regarding vaccine administration and patient eligibility."

SOURCE; Journal of the American Medical Association, December 7, 2005.