FluMist

FluMist is the product name of a nasal spray influenza vaccine manufactured by MedImmune, Inc. first introduced in 2003.^[1] It was the first and (as of 2007) the only live attenuated vaccine for influenza available outside of Europe, and is also called Live Attenuated Influenza Vaccine(LAIV).^[2]

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In 2007, FluMist received additional FDA approval extending the age groups it is approved for to include healthy children two years old and onward.^[3] And the Centers for Disease Control and Prevention's (CDC's) Advisory Committee on Immunization Practices (ACIP), endorsed the needle-free vaccine as a good option for healthy (non-asthmatic) children aged 2 through 4 years.^[4] For comparison, Sanofi-Aventis's injectable influenza vaccine is approved for children 7 months of age and older, and other injectable vaccines from four years of age onward. Injectable influenza vaccine approvals have no upper age limit, while Flumist has not yet been tested or presented for FDA approval for use by persons 50 or older. However, injectable vaccines are known to have a range of side effects such as soreness, redness, swelling, fever, and aches.

Tests against injected (killed virus) vaccinations have shown that FluMist is more effective than needle shots in preventing influenza, especially in children aged 6 to 17 ^{[5] [6]} but one smaller study in adults showed lower effectiveness against influenza B viruses in adults. ^[7]

The current version of the vaccine is called CAIV-T, and is stable for storage in a refrigerator, rather than requiring freezer storage as did the originally-approved formulation.

In June 2006, the National Institutes of Health (NIH) began enrolling participants in a Phase 1 H5N1 study of an intranasal influenza vaccine candidate based on MedImmune's live, attenuated vaccine technology.^[8]

History

FluMist was originally developed by Hunein "John" Maassab, Professor of Epidemiology at the University of Michigan School of Public Health in Ann Arbor, Michigan and later by Aviron under the sponsorship of NIH in the mid-1990s. MedImmune, Inc. purchased Aviron in 2002, and the FDA approved FluMist in June of 2003.^[9] FluMist was first made available in September 2003.

Originally the Food and Drug Administration (FDA) had approved FluMist only for healthy people ages 5 to 49 because of initial concerns over possible side effects. Now Flumist is approved and recommended for healthy children 24 months of age and older. The FDA approved CAIV-T for the same age group (ages 5-49) in August 2006 following completion of phase 3 clinical trials. ^[10] CAIV-T has been approved by the FDA and is the version offered on the market beginning in fall of 2007. Healthy people are the group least likely to suffer serious complications from catching the flu, and although they benefit from vaccination they are encouraged to abstain from vaccination early in the season in years when flu vaccine may be in short supply, to leave an adequate supply for the most vulnerable groups.

A refrigerated formulation was approved for the 2007-2008 flu season can be distributed economically, so that the price differential with shots that hampered sales of the original frozen version of Flumist is now largely or completely a historical footnote. FluMist was initially priced higher than the injectable vaccines, but sold only 500,000 of the 4 million doses it produced its first year on the market, despite a comparative shortage of flu vaccine in fall 2004.^[11] The price was sharply lowered the next year, and the company reports distributing 1.6 million doses in 2005.^[12] Because of the price drop, despite selling almost three times as many doses in 2005, the company reported $21 million in FluMist sales, compared to $48 million the previous year.^[13] Further cuts in pricing had to await FDA approval of a refrigerator-cooled FluMist formulation, as the initial formulation required freezer storage and thawing on demand before administration. In 2006 and 2007, the price premium for FluMist has been reduced to a small fraction over the cost of needle-injected vaccine.

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