Press Releases
MedImmune and National Institutes of Health Begin Clinical Testing of a Live, Attenuated Intranasal Vaccine Against an H5N1 Avian Influenza Virus

GAITHERSBURG, Md., June 15 /PRNewswire-FirstCall/ -- MedImmune, Inc. (Nasdaq: MEDI) announced today that the National Institutes of Health (NIH) has begun enrolling participants in a Phase 1 study of an intranasal H5N1 influenza vaccine candidate based on the company's live, attenuated vaccine technology. Investigators at MedImmune and Johns Hopkins Bloomberg School of Public Health Center for Immunization Research, where the study will be 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 A strains of influenza.

"We believe that our influenza vaccine technology may provide several advantages over the flu shot that will be critically important in protecting people against a pandemic influenza virus," said James F. Young, Ph.D., president, research and development. "In pivotal clinical trials conducted in children 6 months to 59 months of age, our live, attenuated intranasal vaccine technology has been shown to be significantly more effective against seasonal A strains, including those both matched and not matched to the strains used in the vaccine. Additionally, because of its intranasal delivery, our technology may provide a faster and broader immune response, including providing both systemic and mucosal protection at the site where a flu infection takes hold - which is in the nose."

Results from a recently completed Phase 3 clinical study showed that MedImmune's next-generation, investigational influenza vaccine, CAIV-T (cold adapted influenza vaccine, trivalent), was 89 percent more effective than the flu shot in reducing influenza illness caused by matched H1N1 A strains and 79 percent more effective than the flu shot against circulating mismatched H3N2 A strains. CAIV-T is the investigational, next-generation of MedImmune's currently marketed vaccine, FluMist(R) (Influenza Virus Vaccine Live, Intranasal).

The H5N1 vaccine candidate is being developed under MedImmune's Cooperative Research and Development Agreement (CRADA) with the NIH's National Institute of Allergy and Infectious Diseases (NIAID) to produce and test versions of MedImmune's live, attenuated intranasal influenza vaccine for use against different subtypes of potential pandemic influenza strains. This first study is an open-label Phase 1 trial designed to evaluate the safety and immunogenicity of an attenuated, intranasal H5N1 vaccine (based on the A/VietNam/1203/2004 H5N1 strain) in approximately 20 healthy individuals from 18 to 49 years of age. Participants in an isolation unit will receive two doses of vaccine administered 28 to 62 days apart.

The initiation of this trial is the next step in MedImmune's ongoing commitment to ensure the nation is adequately protected against seasonal influenza and prepared for a potential influenza pandemic by using the latest in scientific and medical advancements. Toward this end, the company 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 flu vaccine. Further, MedImmune has notified the World Health Organization and other governmental agencies of its intent to license the key intellectual property for reverse genetics technology, which the company either owns or exclusively licenses, to governmental organizations and companies developing pandemic influenza vaccines for public health purposes. For pandemic vaccines, reverse genetics is important because the technology allows vaccine manufacturers to work with a segment of the infectious, circulating pandemic virus strain's genome rather than directly with the infectious strain itself. Using this technology, it is also possible to make changes to the virus to make it easier and safer to grow.

About CAIV-T

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.

On May 1, 2006 at the Pediatric Academic Societies' annual meeting, MedImmune presented its pivotal Phase 3 study for CAIV-T, entitled, "Comparison of the Efficacy and Safety of Cold-Adapted Influenza Vaccine, Trivalent With Trivalent Inactivated Influenza Vaccine in Young Children 5 to 59 Months of Age." The study included 8,475 children at 249 sites in 16 countries in North America, Europe, the Middle East and Asia. Study participants were randomized one-to-one to receive either CAIV-T or the flu shot during the 2004-2005 influenza season. Each participant also received a placebo nasal spray or placebo injection to preserve the double-blind design of the study. Participants were followed through the influenza season and evaluated to identify illnesses caused by influenza virus. The trial included more than 6,300 previously unvaccinated children with nearly 50 percent of those children less than 2 years of age.

The results of this trial showed that CAIV-T was 55 percent more effective than the trivalent injectable inactivated influenza vaccine (TIV) in reducing influenza illness caused by any influenza strain in children 6 months to 59 months of age, including both matched and mismatched strains. The influenza attack rate was 8.6 percent for study participants receiving the flu shot compared to 3.9 percent for those who received CAIV-T (P <0.001). Against matched strains alone, CAIV-T was 44 percent more effect than the flu shot (attack rates: TIV = 2.4 percent, CAIV-T = 1.4 percent; P<0.001). In this study, CAIV-T was 89 percent more effective than the flu shot in reducing influenza illness caused by the matched H1N1 A strain (attack rates: TIV = 0.7 percent, CAIV-T = 0.1 percent; P<0.001) and 79 percent more effective than the flu shot against circulating mismatched H3N2 A strains (attack rates: TIV = 4.5 percent, CAIV-T = 1.0 percent; P<0.001). No mismatched H1N1 strains or matched H3N2 strains were isolated from subjects in the trial. While there were 16-percent fewer children with illnesses associated with B strains in the CAIV-T group compared to TIV (attack rates: TIV= 3.5 percent, CAIV-T = 3.0 percent), this difference was not statistically significant.

In the study, the overall incidence of adverse events and serious adverse events was similar in both groups except for a higher incidence of runny nose and nasal congestion in CAIV-T recipients (2.5 - 5.6 percent increase) and a higher incidence of injection site reactions in those receiving the flu shot (3.6 - 7.6 percent increase). There were no significant differences through the whole study period for all reported wheezing or for medically significant wheezing (MSW), a pre-specified safety endpoint. Previously unvaccinated children between 6 and 23 months of age had a small but statistically significant increase in MSW at 42 days following their first dose (2.0 percent for TIV vs. 3.2 percent for CAIV-T). Statistically significant differences were not seen beyond 42 days after this first dose or at any time after the second dose.

About FluMist

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.

Please see the Prescribing Information at http://www.flumist.com/pdf/prescribinginfo.pdf, visit http://www.flumist.com, or call 1-877-633-4411 for additional information.

About MedImmune, Inc.

MedImmune strives to provide better medicines to patients, new medical options for physicians, rewarding careers to employees, and increased value to shareholders. Dedicated to advancing science and medicine to help people live better lives, the company is focused on the areas of infectious diseases, cancer and inflammatory diseases. With more than 2,300 employees worldwide, MedImmune is headquartered in Maryland. For more information, visit the company's website at http://www.medimmune.com.

This announcement contains, in addition to historical information, certain forward-looking statements that involve risks and uncertainties, in particular, related to the research and development of a potential pandemic influenza vaccine. Such statements reflect management's current views and are based on certain assumptions. Actual results could differ materially from those currently anticipated as a result of a number of factors, including risks and uncertainties discussed in MedImmune's filings with the U.S. Securities and Exchange Commission. There can be no assurance that such development efforts will succeed, that such products will receive required regulatory clearance or that, even if such regulatory clearance is received, such products will ultimately achieve commercial success.

SOURCE MedImmune, Inc.

CONTACT: Media: Clarencia Stephen, +1-301-398-4073 or Jamie Lacey, +1-301-398-4035, Investors: Peter Vozzo, +1-301-398-4358, all of MedImmune, Inc.