Paris, France - October 26, 2008

High-dose influenza vaccine shows increased immune response among adults 65 years of age and older

Sanofi Pasteur, the vaccines division of sanofi-aventis Group, announced today that an investigational high-dose influenza vaccine demonstrated increased immune responses among adults 65 years of age and older compared with the standard influenza vaccine. The candidate high-dose intramuscular formulation of the influenza vaccine is being developed by sanofi pasteur.

The results were reported today at the 48th Interscience Conference on Antimicrobial Agents and Chemotherapy (ICAAC)/Infectious Diseases Society of America (IDSA) 46th annual meeting.

According to the U.S. Centers for Disease Control and Prevention (CDC), the currently available inactivated influenza vaccine offers public health benefits in reducing influenza-related morbidity and mortality in older adults. Study authors explain, however, that as people age, the immune system tends to weaken. Older adults become not only more susceptible to infections, but also less responsive to vaccination. When infected with the influenza virus, they are less able to mount an immune response to neutralize the attack. “Development of an influenza vaccine that will provide an improved immune response in older adults is important because this population has the highest rates of complications from influenza including hospitalization and death,” said Ann R. Falsey, MD Associate Professor of Medicine, University of Rochester School of Medicine, Rochester, NY; Infectious Diseases Unit, Rochester General Hospital. Approximately 90 percent of the 36,000 average annual influenza-associated respiratory and circulatory related deaths occur among adults 65 years of age and older.

Study Results

The Phase III study of almost 4,000 people 65 years of age and older compared the high-dose influenza vaccine with the standard inactivated influenza vaccine formulated for the 2006-2007 season. The key finding is that the new high-dose vaccine increased the immune responses to all three influenza strains compared with standard vaccine in the study population. An important additional observation was that the increased immune response was also observed in the potentially more vulnerable subset of study participants who had no measurable circulating protective antibodies before receiving their annual influenza vaccine.

In the randomized double-blind study conducted at 30 centers throughout the United States, 2,575 people received the high-dose influenza vaccine and 1,262 received the standard influenza vaccine. The standard influenza vaccine contained 15µg of hemagglutinin (HA) of each of three influenza strains, and the high-dose vaccine contained four times as much, 60µg HA per strain. Both vaccines contained two influenza type A strains (H1N1 and H3N2) and one influenza type B strain.

After 28 days, investigators assessed serum hemagglutination inhibition (HAI) titers in study participants, a standard measurement of the immune response to influenza vaccination. HAI titers are thought by researchers to correlate with increased protection against illness after exposure to influenza. Statistically significant higher HAI titers against all three influenza virus strains were reported in those who received the high-dose vaccine compared with those who received the standard vaccine. Immunogenicity results met pre-defined criteria for overall superiority of the highdose vaccine. Pre-defined criteria for overall superiority in the phase III study was based on geometric mean titers (GMT) and seroconversion, which is defined as either a rise in HAI titer from <1:10 to ≥1:40 post-vaccination or a ≥4-fold increase in HAI titer post-vaccination from a prevaccination titer ≥1:10.

In a post hoc analysis, study investigators also examined post-vaccination immune responses induced by the two vaccines among a subgroup of study participants with no protective antibodies (HAI titers less than 1:10 as measured by their pre-vaccination serum sample). This subset of the study population represents a group who may be at even higher risk for severe influenza disease and its associated complications. Among all study participants, 10 percent were seronegative for H1N1, 8 percent were seronegative for H3N2, and 21 percent were seronegative for the B strain. Twenty-eight days after vaccination, a higher percentage of the subgroup given the high-dose vaccine developed seroprotective HAI titers of 1:40 or greater to each of the three vaccine strains compared with those given the standard vaccine. In addition, mean HAI titers for all strains were higher in the seronegative individuals who received the high-dose vaccine compared with those who received the standard vaccine.

About sanofi-aventis

Sanofi-aventis, a leading global pharmaceutical company, discovers, develops and distributes therapeutic solutions to improve the lives of everyone. Sanofi-aventis is listed in Paris (EURONEXT: SAN) and in New York (NYSE: SNY).

Sanofi Pasteur, the vaccines division of sanofi-aventis Group, provided more than 1.6 billion doses of vaccine in 2007, making it possible to immunize more than 500 million people across the globe. A world leader in the vaccine industry, sanofi pasteur offers the broadest range of vaccines protecting against 20 infectious diseases. The company's heritage, to create vaccines that protect life, dates back more than a century. Sanofi Pasteur is the largest company entirely dedicated to vaccines. Every day, the company invests more than EUR1 million in research and development.
For more information, please visit: www.sanofipasteur.com or www.sanofipasteur.us.

Forward Looking Statements

This press release contains forward-looking statements as defined in the Private Securities Litigation Reform Act of 1995, as amended. Forward-looking statements are statements that are not historical facts. These statements include financial projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions and expectations with respect to future events, operations, products and services, and statements regarding future performance. Forward-looking statements are generally identified by the words “expects”, “anticipates”, “believes”, “intends”, “estimates”, “plans” and similar expressions. Although sanofi-aventis’ management believes that the expectations reflected in such forward-looking statements are reasonable, investors are cautioned that forward-looking information and statements are subject to various risks and uncertainties, many of which are difficult to predict and generally beyond the control of sanofi-aventis, that could cause actual results and developments to differ materially from those expressed in, or implied or projected by, the forward-looking information and statements. These risks and uncertainties include those discussed or identified in the public filings with the SEC and the AMF made by sanofi-aventis, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in sanofiaventis’ annual report on Form 20-F for the year ended December 31, 2007. Other than as required by applicable law, sanofi-aventis does not undertake any obligation to update or revise any forward-looking information or statements.

• Download the press release dated October 26, 2008