MedImmune, Inc. announced that the US Food and Drug Administration (FDA) has approved the company's supplemental biologics license application (sBLA) to use reverse genetics technology to construct new vaccine strains to produce seasonal influenza vaccines, including FluMist (Influenza Virus Vaccine Live, Intranasal) and the next-generation, refrigerator-stable formulation, CAIV-T (cold adapted intranasal vaccine -- trivalent). Creation of new vaccine strains is the first step (and often a production-limiting one) in the influenza vaccine manufacturing process. Use of reverse genetics (also known as "plasmid rescue") technology enhances the safety, specificity, reliability and efficiency with which new vaccine strains can be produced.

"Reverse genetics represents an important breakthrough in commercial influenza vaccine processes by improving the efficiency of producing new influenza vaccine strains on an annual basis," said George W. Kemble, Ph.D., vice president, research and development, vaccines. "This technology enables scientists to replace cumbersome seasonal vaccine strain development methods that were created in the 1960s with modern techniques, which should allow us to accelerate the availability of influenza vaccines to the public.

"For producing pandemic influenza vaccine seeds, reverse genetics has the added benefit of allowing scientists to remove potentially pathogenic portions of the virus, thereby creating a safer production process for the vaccines," Dr. Kemble commented further.

Toward this end, MedImmune has already begun applying its plasmid rescue technology to pandemic research efforts. Last month, the National Institutes of Health (NIH) began enrolling participants in a Phase 1 study of an intranasal H5N1 influenza vaccine candidate based on MedImmune's live, attenuated vaccine technology, which also utilized reverse genetics technology. Investigators at MedImmune and Johns Hopkins Bloomberg School of Public Health Center for Immunization Research, where the study is being conducted, are hopeful that a live, attenuated intranasal influenza vaccine would be as effective against potential pandemic A strains as it has been shown to be against seasonal matched and mismatched A strains of influenza.

Most influenza vaccine manufacturing companies and governmental agencies are now using reverse genetics technology in their development of pandemic vaccine candidates because it allows them to avoid working directly with the infectious, circulating pandemic strains. As the owner or exclusive licensee of the key patent estates for use of the reverse genetics technology in human influenza vaccines, MedImmune remains committed to making sure that the technology is accessible to government institutions and industry manufacturers. As such, the company has offered other influenza vaccine manufacturers non-exclusive licenses to this intellectual property estate for use in manufacturing seasonal or pandemic vaccines.

As the manufacturer of FluMist, the first major innovation in influenza vaccine technology in more than 50 years, MedImmune continues to expand upon its commitment to ensure the nation is adequately protected against seasonal and pandemic influenza by using the latest in scientific and medical advancements. In addition to the activities described above, the company also recently received a $170-million contract from the U.S. Health and Human Services Department to expedite the development of cell culture-based production of its influenza vaccine.

Further, the company also recently submitted its first lots of commercial FluMist for the 2006-2007 influenza season to the FDA for approval and release. The company expects to have all lots approved and released for commercial sale by the first week in September. Should all things continue on track, MedImmune anticipates shipping its first doses of FluMist for the upcoming season to customers by the end of July 2006.

FluMist is indicated for active immunization for the prevention of disease caused by influenza A and B viruses in healthy children and adolescents, 5 to 17 years of age, and healthy adults, 18 to 49 years of age. There are risks associated with all vaccines, including FluMist. Like any vaccine, FluMist does not protect 100 percent of individuals vaccinated. In studies of people between the ages of 5 and 49 years, runny nose was the most commonly reported side effect. Other common side effects included various cold-like symptoms, such as headache, cough, sore throat, tiredness/weakness, irritability, and muscle aches.

FluMist should not be used, under any circumstances, in anyone with an allergy to any part of the vaccine, including eggs; in children and adolescents receiving aspirin therapy; in people who have a history of Guillain-Barre syndrome; and in people with known or suspected immune system problems. Pregnant women and people with certain medical conditions, asthma, or reactive airways disease should not get FluMist.

CAIV-T is an investigational intranasal, cold-adapted trivalent influenza vaccine. It is the next-generation, refrigerator-stable formulation of FluMist, which is a frozen, live attenuated cold-adapted trivalent influenza vaccine. To date, the safety, tolerability and efficacy of CAIV-T has been studied in both healthy and at-risk populations between the ages of 6 weeks and 98 years.