MedImmune Profitable biotech; 18 years old ~$1.3B revenues; $438M* R&D (2006) As of 12/31/06, ~$1.5B cash ~2,500 employees; HQ in Gaithersburg, Md. Three marketed products; ~45 candidates in R&D Infectious disease, cancer and inflammatory disease Innovative, proprietary products, unmet medical needs Leader in pediatrics, respiratory infectious disease, antibodies and vaccines *Excludes impact of share-based compensation expense.

$87M Prevent RSV in high-risk infants Palivizumab Chemo-/radio- protectant Amifostine Prevent influenza Live attenuated influenza vaccine Marketed Products Compound Indication 2006 Revenues $1.1B $36M Product

Numax® RSV MAb (AI Ex-US) EBV subunit vaccine (GSK) S.pneumoniae vaccine (GSK) PIV-3-vectored RSV vaccine Live attenuated RSV vaccine Live attenuated PIV-3 vaccine Pandemic influenza vaccines Live attenuated CMV vaccine Cell culture FluMist 3rd generation RSV MAb Anti-RSV drug Live attenuated PIV-1 vaccine Live attenuated PIV-2 vaccine Anti-hMPV MAb Live attenuated hMPV vaccine Anti-Staph heteropolymer MAb Anti-Candida heteropolymer MAb Anti-IL-9 MAb (asthma) Anti-IFN MAb (SLE) Anti-IL-5R MAb (asthma) Anti-IFNR MAb Anti-CD19 MAb Anti-CD20 MAb Anti-CD22 MAb Anti-HMGB-1 MAb Anti-YKL40 MAb Anti-ICOS MAb Anti-RAGE MAb Anti-IL-6 MAb Anti-C5a MAb MedImmune Pipeline Clinical Preclinical HPV vaccine (GSK/MRK) Anti-CD2 T-cell MAb (CTL) Anti-CD19 BiTE® (NHL) Anti-Hsp90 drug (GIST/NSCLC) Anti-Hedgehog drug Anti-EphA2 BiTE Anti-CEA BiTE Anti-EphA2 conjugate Anti-EphB4 MAb Anti-Ephrin B2 MAb Anti-EphA4 MAb Anti-CD19 MAb Anti-CD20 MAb Anti-CD22 MAb Anti-ALK MAb Anti-cMet Avimers

MedImmune Operations Frederick, MD Monoclonal Antibody Manufacturing Speke, England FluMist Bulk Manufacturing Philadelphia, PA FluMist Blend/Fill/Package Nijmegen, Netherlands Ethyol Manufacturing, Clinical Fills Mountain View, CA Vaccine R&D Bensalem, PA FluMist Warehouse Santa Clara, CA Vaccines R&D, Vaccine Pilot Plants Louisville, KY Product Distribution Gaithersburg, MD Headquarters and R&D and Pilot Plant Rockville, MD FluMist Cell Culture Pilot Plant

General Business:

Q: Why did we make this decision now? Why is this in the best interest of shareholders?

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We had several major pharmaceutical companies express interest, and we conducted a full and open evaluation process to provide to our board of directors as much information as possible to allow them to make an informed decision on the way to achieve the best value for all shareholders. As we have said before, MedImmune is a rare asset, and the value achieved in this transaction demonstrates the recognition of what has been built over the 19-year history of the company.

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The value of $58 per share represents a premium of about 53% over the price of MedImmune stock on April 11 and an 85% premium to the average price over the past year.

Q: What happens next? Do we have to have a shareholder vote? Does the SEC have to approve? How long will this take? Is there a chance that we won’t be bought after all?

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Next steps include a tender offer that will go out in the next 10 days that will instruct shareholders how to turn in their shares for cash.

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There is a 20 business day period that the tender offer will be in place. At the end of the 20 days, we will count the number of shares tendered. If more than 90% are tendered, then the transaction will close within a couple of days as long as all of the anti-trust clearances have been received. If less than 90% of shares are tendered, then we have to conduct a special shareholders’ meeting about 6-8 weeks after the tender period ends. Then we will close within a couple of days, as long as anti-trust clearances have been received.

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Signing an agreement is the first stage of this process, and the transaction won’t be final until we close. There is always a chance that it won’t close, but that chance is highly unlikely.

Employment:

Q: Will I have a job in the new organization? How will I find out?

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Between signing and closing, you should continue to conduct business as usual.

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MedImmune, AstraZeneca and Cambridge Antibody Technologies will form a transition team that will deal with integration questions and the operating model going forward. Until then, the best thing you can do is continue to execute on our business plan.

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AZ has stated that they intend to maintain and build on the integrity and capabilities of MedImmune to build a new, fully functioning biologics and vaccines business.

Retention:

Q: If I retain my job, who will I report to and how will the organization change? Will I get to meet any of the new management?

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Between signing and closing, you should continue to conduct business as usual.

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MedImmune, AstraZeneca (AZ) and Cambridge Antibody Technologies (CAT) will form a transition team that will deal with integration questions and the operating model going forward. Until then, the best thing you can do is continue to execute on our business plan.

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As we get closer to completing the transaction, we would expect to have introductory meetings with our AZ and CAT counterparts so we can become more familiar. We would also expect to introduce members of AZ and CAT senior management to MedImmune as soon as practicable.

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Current MedImmune management will continue to manage the operation as part of AstraZeneca. David Mott, MedImmune’s CEO, will report directly to David Brennan, AstraZeneca’s CEO, and will be a member of AZ’s Senior Executive Team.

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Our current compensation structure is protected for one year. We have also established a one-time retention grant for employees who are here one year from closing. You may get specific details and information on the retention plan by contacting Employee Communications and/or Human Resources.

Positions Eliminated/Severance:

Q: If my old job is eliminated, can I apply for a different job in the company?

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Between signing and closing, you should continue to conduct business as usual.

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MedImmune, AstraZeneca and Cambridge Antibody Technologies will form a transition team that will deal with integration questions and the operating model going forward. Until then, the best thing you can do is continue to execute on our business plan.

Q: If I don’t have a job, what sort of severance package might I expect?

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We have established a severance program for any employee whose job is eliminated within 12 months of closing. You may get specific details and information on the severance program by contacting Employee Communications and/or Human Resources.

Stock shares:

Q: Can I sell stock I own now?

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The company-wide blackout was lifted on Tuesday, April 24. However, certain people involved in the quarterly earnings process will still be under the normal trading black out until we file our 10Q for the first quarter 2007 which is expected to be early next week.

Options:

Q: What happens to my stock options, both vested and unvested?

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At closing, unvested options will be accelerated and become fully vested. All in-the money options will be “cashed out” at $58 per share and the gain over the exercise price will be paid out to employees, less applicable taxes.

Benefits:

Q: Do my benefits change and if so, when and how?

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Between signing and closing, our benefit programs will remain the same.

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After closing, we would expect to participate in benefit programs comparable to what we have today.