January 2003
BETHESDA, Md. — The cold-adapted, intranasal influenza vaccine (CAIV) (FluMist, MedImmune and Wyeth) took one step closer to approval when an FDA advisory panel said that efficacy and safety data for healthy individuals aged 5 through 49 warranted approval of the product.
The Vaccines and Related Biological Products Advisory Committee (VRBPAC) said that while safety data were adequate in healthy adults age 50 to 64, efficacy data were lacking.
The CAIV last appeared before the panel in July 2001. The biotech firm Aviron sought approval of the product for all healthy individuals age 1 to 64, but the panel rejected the license application saying that safety data were lacking for the youngest children.
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Influenza virus kills about 20,000 Americans each year and causes about 70 million missed workdays and 38 million lost school days. |
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Source: CDC |
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Several committee members suggested that Aviron seek an indication only for children age 2 and older since most of the data presented to the panel at that time were for older children.
Company officials expressed frustration with the panel’s request for additional data. The NIH first developed the technology for the product in the 1960s and Aviron only acquired the product in 1995 after numerous clinical trials had already been run.
MedImmune purchased Aviron in early 2002 and continued to develop FluMist with Wyeth Pharmaceuticals. Wyeth recently decided to drop production of its injectable influenza and pneumococcal vaccines to focus on CAIV.
This time around, MedImmune asked for approval in individuals 5 and older because clinical trials have shown a higher incidence of moderately severe asthma in FluMist recipients, peaking between 18 and 39 months of age. However, it is not known whether children exposed to wild-type influenza experience a similar increase in symptoms.
The FDA asked its panel to consider the safety and efficacy data in three specific age ranges: 5 to 17 years, 18 to 49 years and 50 to 64 years of age. The age breakdowns reflect the new emphasis on age-based vaccine recommendations rather than risk-based recommendations.
The panel voted 17-to-1 in favor of safety data in children 5 to 17 years and 14 to 4 in favor of efficacy. For adults 18 to 49, the panel voted 17-to-1 in favor of both safety and efficacy.
But when asked about adults 50 to 64, the committee was hesitant in approving the safety data and voted 10-to-8 in favor. For the efficacy data, the panel rejected the evidence 14-to-4.
Most of the data for older adults age 50 to 64 came from a large effectiveness trial in Minnesota. Although that trial showed the vaccine to be effective, most panel members were still uncertain about the efficacy of FluMist.
Though the FDA usually follows the advice of its advisory panels, the decision is still not binding. MedImmune officials said it would continue to work with the FDA to get the vaccine approved in time for the 2003-2004 influenza season.
In clinical trials, FluMist was given to over 20,000 recipients. Runny nose and nasal congestion were the most common adverse events.
Influenza virus kills about 20,000 Americans each year and causes about 70 million missed workdays and 38 million lost school days.
The injectable influenza vaccine is currently recommended for all individuals over the age of 50 and all individuals at high risk for complications from influenza—including those with chronic conditions. However, the vaccine is underutilized in adults and approximately 10% to 15% of the supply goes unused each year.
The Advisory Committee on Immunization Practices (ACIP) is also considering adding children 6 to 23 months of age and household contacts to the recommendations. There has been speculation that adding young children would mean recommendations for more people than there are influenza doses.
If FluMist were approved for all healthy individuals 5 to 49 years old, it would indirectly affect the ACIP’s decision by freeing up some of the injectable supply for use in other age ranges.