MedImmune And National Institutes Of Health Begin Clinical Testing Of A Live, Attenuated Intranasal Vaccine Against An H5N1 Avian Influenza Virus

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