News Pressroom

January 30, 2003

MedImmune Receives Complete Response Letter from FDA for FluMist(TM), an Intranasal Flu Vaccine

GAITHERSBURG, Md., Jan. 30 /PRNewswire-FirstCall/ -- MedImmune, Inc. (Nasdaq: MEDI) announced today that it has received a Complete Response Letter (CRL) from the U.S. Food and Drug Administration (FDA) for its Biologics License Application (BLA) for FluMist(TM) (Influenza Virus Vaccine Live, Intranasal), a nasally delivered flu vaccine. FDA is requesting clarification and additional information relating to data previously submitted. No additional clinical trials have been requested.

"We are pleasantly surprised to have received this Complete Response Letter from the FDA earlier than anticipated," said David M. Mott, MedImmune's chief executive officer. "We expect to fully respond to the five questions contained in the letter within a week and look forward to continuing to work with the FDA toward the approval of FluMist."

If approved by the FDA, FluMist would be the first and only intranasal influenza vaccine in the United States, and would be marketed by MedImmune and Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE) as part of an ongoing global collaboration agreement.

On December 17, 2002, the U.S. Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee (VRBPAC) voted favorably on the questions of safety and efficacy for FluMist in preventing influenza in healthy children, adolescents and adults ages 5 through 49. Advisory committees provide the FDA with independent opinions and recommendations from outside experts on applications to market new drugs and on FDA policies. While advisory committee recommendations are valuable, all final decisions related to a regulated product are made by the FDA.

The original BLA for FluMist was submitted to the FDA in October 2000 by Aviron, a California-based vaccines company MedImmune acquired in January 2002. Subsequently, MedImmune has submitted answers to questions raised by the FDA in two previous CRLs issued by the FDA in August 2001 and July 2002, respectively.

FluMist is a live, attenuated vaccine delivered as a nasal mist being developed by MedImmune for the prevention of influenza. Clinical trials suggest that FluMist is effective in reducing the incidence of influenza in healthy children and adults. FluMist also offers certain potential advantages in its administration by nasal spray, such as eliminating the unpleasantness of needle-based injectable vaccines and local injection site reactions.

Influenza is the most common cause of medically attended acute respiratory illness in the U.S. often involving fever, chills, muscle weakness, cough, sore throat, nasal congestion, headache and general malaise. According to the Centers for Disease Control and Prevention and the American Lung Association, 20 to 50 million people are infected annually in the U.S., causing 70 million lost work days(1), 38 million lost school days(2), and 20,000 to 50,000 deaths per year (primarily in the elderly)(3). The annual burden of the disease to society has been estimated at $15 billion.

Conference Call & Webcast

In conjunction with its 2002 Fourth Quarter and Year End Financial results, also released today, MedImmune will conduct a conference call and live webcast at 8:00 a.m. U.S. (EST) today to discuss its 2002 earnings, the most recent Complete Response Letter for FluMist, and other business results. The webcast may be accessed on MedImmune's website at www.medimmune.com. A replay of the webcast will also be available via our website until February 6, 2003. An audio replay of the webcast will be available beginning at 11:00 a.m. U.S. (EST) on January 30, 2003 until midnight February 6, 2003 by calling (888) 286-8010. The passcode for the audio replay is 71815.

MedImmune is a leading biotechnology company focused on researching, developing and commercializing products to prevent or treat infectious disease, autoimmune disease and cancer. MedImmune actively markets three products, Synagis(R) (palivizumab), Ethyol(R) (amifostine) and CytoGam(R) (cytomegalovirus immune globulin intravenous (human)), and has several products in clinical testing. MedImmune employs approximately 1,600 people, is headquartered in Gaithersburg, Maryland, and has additional operations in Frederick, Maryland, as well as Pennsylvania, California, the United Kingdom and the Netherlands. For more information on MedImmune and full prescribing information for the company's marketed products, visit the company's website at www.medimmune.com.

(1) Adams PF, Hendershot GE, Marano MA. Current estimates from the

        National Health Interview Survey, 1996 National Center for Health
        Statistics.  Vital Health Sta. 10(200) 1999

(2) Adams PF, Hendershot GE, Marano MA. Current estimates from the

        National Health Interview Survey, 1996 National Center for Health
        Statistics.  Vital Health Sta. 10(200) 1999

(3) CDC. ACIP/MMWR. 2002; 51 (no, RR-3):1-31

This announcement may contain, in addition to historical information, certain forward-looking statements that involve risks and uncertainties, including risks and uncertainties surrounding the potential approval, launch and successful acceptance of FluMist in the marketplace. 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 the company's filings with the U.S. Securities and Exchange Commission. The company is developing several products for potential future marketing. 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 were received, such products would ultimately achieve commercial success. SOURCE MedImmune, Inc.

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/CONTACT: Investors, William Roberts, Manager, Investor Relations, +1-301-527-4358, or Media, Jamie Lacey, Associate Director, Public Relations, +1-301-527-4358, both of MedImmune, Inc./