Sanofi Pasteur Files for Approval in Thailand and Australia of IMOJEV(TM), Single-dose Japanese Encephalitis Vaccine

LYON, France -

- Novel Vaccine IMOJEV(TM) for the Prevention of Japanese Encephalitis in Children and Adults Living in Asia

Sanofi Pasteur, the vaccines division of sanofi-aventis group, (EURONEXT: SAN and NYSE: SNY), announced today that it has filed marketing authorization applications in Thailand and Australia for IMOJEV(TM), its single-dose vaccine against Japanese encephalitis (JE). This novel vaccine is aimed for the prevention of JE in children and adults living in endemic countries in Asia. Three billion people live in countries where JE is endemic1.

Japanese encephalitis is a viral infection that affects 30,000 to 50,000 people each year in Asia, of which 10,000 die. JE is the most frequent and most severe form of viral encephalitis, and is a leading cause of neurological infections in Asia 2. There is no specific treatment for JE and the virus cannot be eradicated given its circulation in pigs and birds.

“The goal of sanofi pasteur is to provide an innovative Japanese encephalitis vaccine to people who most need it in order to improve public health in countries where the disease is endemic,” said Wayne Pisano, chief executive officer of sanofi pasteur. “We believe IMOJEV(TM) single-dose vaccine has the potential to transform JE vaccination in Asia and help reduce the burden of this devastating disease.”

“Japanese encephalitis control through immunization is feasible and it reduces the burden of disease,” said John Wecker, Global Program Leader, Immunization Solutions at PATH. “Single-dose vaccines hold significant advantages to increase the immunization coverage rate and simplify vaccination campaigns.”

The marketing authorization files are under review by the Therapeutic Goods Administration in Australia (TGA), and by the Food and Drug Administration in Thailand (TFDA) which is giving the vaccine a fast track review. Clinical studies, involving over 3,800 children and adults, evaluated the safety and ability to generate a protective immune response with only one dose of this novel vaccine.

The clinical data supporting the use of IMOJEV(TM) in children and in adults have been generated in multi-center studies conducted in the United-States, Australia, Thailand, and the Philippines with more than 2,400 adults and 1,400 children receiving IMOJEV(TM).

The safety and immunogenicity of IMOJEV(TM) was compared to a licensed Japanese encephalitis vaccine (JE-VAX(R)) and placebo in adults and to a control vaccine in children. A pivotal Phase III study in adults showed that a single dose of IMOJEV(TM) is as immunogenic as three doses of JE-VAX(R). A single administration of IMOJEV(TM) elicits a protective level of neutralizing antibodies in 93.6% and 99% of subjects 14 days and one month after vaccine administration, respectively. A Phase III study in children showed that 95% of JE virus naive subjects are seroprotected one month after a single dose of IMOJEV(TM). The vaccine is well tolerated and there was no indication during the clinical development program of any safety concerns. The frequency of local and systemic reactions was comparable to those reported after administration of a placebo or a control vaccine in adult as well as in pediatric populations.

About Japanese encephalitis

Japanese encephalitis is a disease caused by a flavivirus that affects the membranes around the brain. Most JE virus infections are mild (fever and headache) or without apparent symptoms, but up to 1 in 200 infections results in severe disease characterized by rapid onset of high fever, headache, neck stiffness, disorientation, coma, seizures, spastic paralysis and death. The case fatality rate is 30-35% among those with disease symptoms; 50% of those who survive suffer from lasting damage to the central nervous system. In areas where the JE virus is common, encephalitis occurs mainly in young children (1).

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 2008, 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 EUR 1 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 sanofiaventis’ 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 sanofi aventis’ annual report on Form 20-F for the year ended December 31, 2008. Other than as required by applicable law, sanofi-aventis does not undertake any obligation to update or revise any forward-looking information or statements.

References:

1. United Nations The United Nations urbanization prospects: the 2005 revision. POP/DB/WUP/Rev.2005/1/F1. New York: United Nations; 2005.

2. Japanese encephalitis. WHO Initiative for Vaccine Research

www.who.int/vaccine_research/diseases/vector/en/index1.html

www.sanofipasteur.com

www.sanofipasteur.us

Source: Sanofi Pasteur

Contacts: Global Media Relations, Pascal Barollier, T: +33(0)4-37-37-50-38, pascal.barollier at sanofipasteur.com; US Media Relations, Len Lavenda, T: +1-570-839-4446, len.lavenda at sanofipasteur.com