Prepared by MERRILL CORPORATION
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MedImmune Contacts:
Lori Weiman
Senior Director, Corporate Communications
301-527-4321

Will Roberts
Manager, Investor Relations
301-527-4358

    On December 3, 2001, MedImmune announced that it has entered into a definitive merger agreement under which it will acquire Aviron through an exchange offer and merger transaction. Attached and incorporated herein by reference in its entirety as Exhibit 1 is a copy of a slide-show presentation given to investors by MedImmune to further explain the transaction.


    Filed by MedImmune, Inc.
Pursuant to Rule 425 under the Securities Act of 1933
Subject Company: Aviron
Commission File No. 000-20815

LOGO

Jennison Associates Presentation
December 2001



DISCLOSURE NOTICE:

    This presentation may contain, in addition to historical information, certain forward-looking statements that involve risks and uncertainties. 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 and Aviron's filings with the SEC. MedImmune and Aviron are developing 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. There can be no assurance that the offer and merger will close or that Aviron will be integrated successfully or without unanticipated costs.

    We urge Aviron stockholders and other investors to read the registration statement on Form S-4, Schedule TO, preliminary prospectus, supplements, final prospectus and other exchange offer documents which have been filed or will be filed by MedImmune with the Securities and Exchange Commission and the related solicitation/recommendation statement filed by Aviron with the SEC. These documents contain important information which should be read carefully before any decision is made with respect to the offer. Documents filed with the SEC are available for free at the SEC's website at www.sec.gov. Documents are available for free from MacKenzie Partners, Inc., 800-322-2885.



Agenda



MedImmune, Inc.


LOGO   Synagis®


LOGO


 


•  Humanized monoclonal antibody
    — Only MAb approved for infectious disease
•  Launched in U.S. September 1998
•  Prevention of serious lower respiratory tract disease caused by RSV in high risk infants
•  Approved in 46 countries; ABT ex-US distributor, co-promotes in U.S.

LOGO   Worldwide Synagis® Sales
Seasonal Comparison
(millions)

LOGO


LOGO   Ethyol®



LOGO



 



•  Cytoprotectant agent
    — Reduce cisplatin toxicities in ovarian and NSCLC (1996)
    — Prevent radiation induced xerostomia in H/N (1999)
•  MEDI regained U.S. marketing rights October '01
•  Schering-Plough ROW distributor
•  Current annualized worldwide sales $65M ($44M U.S.)


Strong R&D Pipeline

     LOGO



Aviron Acquisition



Transaction Details



Strategic Rationale
Excellent Strategic Fit



Strategic Rationale
Unique Ability to Assess and Execute

• R&D   Jim Young, PhD

• Clinical

 

Frank Top, MD
Ed Connor, MD

• Regulatory

 

Peter Patriarca, MD

• Mfg./QC/QA

 

Gail Wasserman, PhD
Ed Goley
Ben Machielse

• Marketing

 

Jeff Hackman


Strategic Rationale
Excellent Financial Fit



Strategic Rationale
Excellent Financial Fit

Financial Goals

  2002
  2003
  2006
Revenues   $900M   $1.1-$1.25B   >$2.1B
Cash EPS   $0.65-$0.70   $1.15-$1.20   >$2.50

2006 Operating Metrics (Goals)



Strategic Rationale
Create Premier Biotech Company



The FluMist Opportunity



Influenza



Impact of Influenza

Source: MMWR 2001
Source: American Lung Association, 3/01



Influenza-related Morbidity and Mortality

     LOGO

Glezen WP. Emerging infections: pandemic influenza. Epidemiol Rev. 1996; 18(1), 64-76.



Influenza




FluMist™

 

LOGO

Live   Active viral replication   X >20,000 vaccinated in ~20 studies

Attenuated

 

Mild Infection

 

X Positively viewed by pediatric community

Cold-adapted Temperature-sensitive

 

Replication restricted mainly to nasopharynx

 

X Anticipated by recommending bodies

Trivalent

 

A (H3N2, H1N1), B

 

X Significant public health impact

Dose = 0.5 ml (~107 TCID50)
0.25 ml into each nostril

 

 


Efficacy

Endpoint

  % Efficacy
  95% CI
Culture Confirmed Flu   91.7   87.7, 94.4

Febrile Illness

 

93.6

 

89.7, 96.0

Otitis Media

 

96.2

 

87.6, 98.8

Lower Respiratory Illness

 

95.2

 

62.2, 99.4
Endpoint

  % Reduction
  P-Value
Missed daycare/preschool/school days        
  Any Illness   12.8   0.07
  Culture Positive Illness   93.2   <0.001
Healthcare Provider Visits        
  Any Illness   11.2   0.02
  Culture Positive Illness   92.1   <0.001
Parental Lost Work        
  Any Illness   12.6   0.17
  Culture Positive Illness   93.0   <0.001


Frozen FluMist BLA
Under FDA Review



VRBPAC Efficacy Discussion

Question 1:   Are the data adequate to support the efficacy of FluMist?

 

 

Adults 18-64 years of age?
Yes 13-2

 

 

Children 1-17 years of age?
Yes 8-7

 

 

Children 2-17 years of age?
Yes 13-2

 

 

 


VRBPAC: Safety Discussion


Question 2:

 

Are the data adequate to support the safety of FluMist in the population in which an indication is being sought (i.e., 1-64 years)?

 

 

No 10-4

 

 

6 of 10 no votes were provisional
pending final FDA data analysis

 

 

Issues

 

 

•  Pneumonia

 

 

•  Asthma

 

 

•  Concurrent use

 

 

 


Pediatric Pneumonia

 
  FluMist
  Placebo
 
Study

 
  N
  Cases
  >21d
  N
  Cases
  >21d
 
AV006-Y1   1070   8   6   532   2   1  
AV006-Y2   917   2   1   441   0   0  
AV007   400   1   1   100   0   0  
AV0012-Y1   4298   2   1              
AV0012-Y2   5251   6   4              
AV0015   949   1   1              
AV0017   1175   3   3   70   0   0  
AV0019   6495   14   10   3238   10   6  
Total   20,555   37   27   4,381   12   7  
Percent       0.18 % 0.13 %     0.21 % 0.16 %


Asthma Episodes (All Doses)
AV019—Healthy Children

Age

  FluMist
n/N

  Placebo
n/N

  Rate per 1000
person-months
FluMist/Placebo

  p Value
1-17 years   58 / 6473   30 / 3216   4.6 / 4.8   p=0.422
1-8 years   45 / 3769   21 / 1868   5.1 / 4.8   p=0.418
18-36 months   16 / 728   2 / 369   9.3 / 2.3   p=0.019
12-17 months   1 / 171   3 / 90   2.5 / 14.4   p=0.067


Safety Database
(approximate number of participants)

 
  Pre-Aviron
Data Set

  Included in
BLA

  Included in
Safety Update

Healthy Children   2,600   6,000   18,000
Healthy Adults   4,600   3,700   4,000
High Risk   900   700   2,000
Total   8,100   10,400   24,000


Complete Response Letter



Potential Label

Indication   Prevention of influenza in healthy persons age 18mo - 64yrs

ClinPharm

 

93% Efficacy
37% ARROW flu-assoc. febrile otitis media Reduction in direct/indirect costs

Precautions/
warnings

 

Do not administer to persons with prior Hx wheezing; do not administer with other vaccines

Side Effects

 

Mild URI Sx in 20-50%
Significant fever 2-5%

Dosage/admin

 

0.5 cc intranasally (0.25 cc/nostril) 2 doses 30-60d apart for age <9yrs

LOGO   Conclusions

X Important medical advance

X New approach to immunization

X Data supports efficacy

X Draft clinical responses address major CR issues

X Primary issues that may affect timing and labeling

X Data support high likelihood of approval



FluMist™ Commercial Structure



R&D Programs



Aviron Acquisition





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DISCLOSURE NOTICE
Agenda
MedImmune, Inc.
Strong R&D Pipeline
Aviron Acquisition
Transaction Details
Strategic Rationale Excellent Strategic Fit
Strategic Rationale Unique Ability to Assess and Execute
Strategic Rationale Excellent Financial Fit
Strategic Rationale Excellent Financial Fit
Strategic Rationale Create Premier Biotech Company
The FluMist Opportunity
Influenza
Impact of Influenza
Influenza-related Morbidity and Mortality
Influenza
Efficacy
Frozen FluMist BLA Under FDA Review
VRBPAC Efficacy Discussion
VRBPAC: Safety Discussion
Pediatric Pneumonia
Asthma Episodes (All Doses) AV019—Healthy Children
Safety Database (approximate number of participants)
Complete Response Letter
Potential Label
FluMist™ Commercial Structure
R&D Programs
Aviron Acquisition