sanofi pasteur H5N1 Pre-Pandemic Vaccine Neutralizes Additional Circulating H5N1 Virus

Vienna, Austria (ots/PRNewswire) - sanofi pasteur, [NYSE: SNY] the
vaccines business of the sanofi-aventis Group, today announced that
its H5N1 pre-pandemic vaccine induces antibodies that neutralize
additional H5N1 circulating virus not included in the original
vaccine formulation. These data, presented at the 2nd International
Conference on Influenza Vaccines for the World held in Vienna,
Austria, further demonstrate the value of sanofi pasteur candidate
vaccine for pandemic preparedness.

"These encouraging data show the potential for a pre-pandemic
vaccine to offer broad protection by inducing antibodies that
neutralize H5N1 from more recent circulating viruses. Improving the
repertoire of antibody response is an important goal for pandemic
influenza vaccines" said Maria Zambon, MD, (Deputy Director Virus
Reference Division, Health Protection Agency, London), who conducted
the laboratory tests.

Analysis of blood samples from volunteers who participated in the
first phase I clinical trial conducted in 2005 with H5N1 pre-pandemic
vaccine from sanofi pasteur showed the potential of the vaccine to
protect against recent H5N1 circulating viruses.

Vaccinated volunteers developed serum antibodies that were able to
neutralize diverse H5N1 viruses (A/turkey/Turkey/1/2005 wt
(wild-type) and rg (reverse-genetic) clade 2, and A/Vietnam/1194/2004
wt and rg clade 1). The tested vaccine contains the
A/Vietnam/1194/2004 rg strain. These more recently circulating H5N1
viruses have caused human infections in several European countries in
2005 and 2006, and continue to cause infections in parts of South
East Asia.

Among volunteers who developed antibodies to the vaccine,
cross-neutralization results were similar in those who received high
antigen (30microg) and those who received lower antigen (7.5microg)
vaccine doses. Results were also similar in volunteers who received
alum-adjuvanted and non-adjuvanted vaccine (alum is an additive
commonly used to increase the immune response to vaccines). The
ability to provide cross-protection against diverse influenza strains
with less antigen is an important feature for any pandemic or
pre-pandemic vaccine, as it will allow for production of more doses
to protect the largest number of people in the case of a pandemic.

These new data reinforce conclusions of the sanofi pasteur phase I
study published in May 2006 [1] which demonstrated multiple dosage
formulations of the H5N1 pre-pandemic vaccine candidate generates an
immune response with and without an adjuvant.

Data answer World Health Organization (WHO) calls for
demonstration of cross-reactivity

The latest data on the sanofi pasteur pre-pandemic candidate
vaccine provide information called for in World Health Organization
(WHO) recommendations that data be gathered on cross-reactivity and
cross-protection against viruses from different clades as an
essential element of pandemic preparedness [2].

H5N1 Viruses isolated from animals and humans since 2003 separate
into two distinct genetic groups (clades) of closely related viruses.
Clade 1 viruses circulated in Cambodia, Thailand and Viet Nam and
were responsible for human infections in those countries in 2004 and
2005. Clade 2 viruses circulated in birds in China and Indonesia in
2003-2004. In 2005-2006, Clade 2 spread westwards to the Middle East,
Europe and Africa [2].

Pandemic Influenza Overview

Influenza is a highly infectious virus that spreads easily from
person to person, primarily when an infected individual coughs or
sneezes. An influenza pandemic is a global epidemic of an especially
virulent virus, newly infectious for humans, with the potential to
cause severe morbidity and mortality. According to the World Health
Organization (WHO), the next pandemic is likely to result in 1 to 2.3
million hospitalizations and 280,000 to 650,000 deaths in
industrialized nations alone. Its impact is expected to be even more
devastating in developing countries. In an attempt to minimize the
impact of a pandemic, many countries are developing national and
transnational plans against an eventual influenza pandemic situation.

sanofi pasteur and Pandemic Preparedness

sanofi pasteur, the vaccines business of the sanofi-aventis Group,
is committed to global pandemic preparedness. As the world leader in
research, development and manufacturing of influenza vaccine, sanofi
pasteur is actively involved in other projects in the U.S. and
Europe, with the goal of developing a vaccine to protect against a
pandemic influenza virus.

sanofi pasteur is investing in a major expansion of its influenza
vaccine production capacity in the US, and also of its vaccine
production capacity in France (Val de Reuil facility).

In Europe, sanofi pasteur initiated and runs a large range of
projects:

- In France, sanofi pasteur sponsored the first clinical trials of
an H5N1 influenza vaccine candidate that compared vaccines with and
without adjuvants [1].

- In France, sanofi pasteur was awarded a contract by the French
Ministry of Health to produce a 1.4 million dose stockpile of the
H5N1 candidate studied in the above-mentioned trial. By this
agreement, the company could also provide enough vaccine to protect
up to 28 million people in France in the event of a pandemic being
declared, once the actual virus strain responsible is identified.

- In Italy, in February 2006, sanofi pasteur provided candidate
H5N1 vaccine to the Ministry of Health and entered into an agreement
to provide an actual pandemic strain of vaccine, once a pandemic has
been declared.

In the U.S., sanofi pasteur has a number of pandemic-related
agreements with the U.S. government involving development of pandemic
vaccine stockpiles, production of investigational doses and the
development of cell culture technology, including:

- In May 2004, sanofi pasteur contracted with the U.S. National
Institutes for Allergy and Infectious Diseases (NIAID) to produce
investigational doses. The doses were shipped to the NIAID in March
2005. The studies were completed in 2005 and the results were
published in New England Journal of Medicine [3].

- In September 2004, the company signed a contract with HHS to
produce two million doses of bulk vaccine derived from the H5N1 viral
strain. The bulk doses were produced and are being stored and can be
formulated and filled upon government request.

- In November 2004, the HHS awarded a contract to sanofi pasteur
to expand and safeguard the egg supply needed to produce influenza
vaccine and to formulate each year investigational doses for a
potential pandemic influenza vaccine.

- In April 2005, the HHS awarded a contract to sanofi pasteur to
accelerate the development of a cell-culture influenza vaccine in the
U.S. and to design a U.S.-based cell-culture vaccine manufacturing
facility.

- In September 2005, the HHS awarded a contract to sanofi pasteur
to produce a vaccine to help protect against the H5N1 influenza virus
strain. The $150 million contract calls for sanofi pasteur to
manufacture the vaccine in bulk concentrate form at its U.S.
headquarters in Swiftwater, PA. The agreement provides for additional
fees to be paid to sanofi pasteur for storage of the vaccine as well
as for formulation and filling of the vaccine upon government
request.

- In February 2006, sanofi pasteur supplied NIAID with 15,000
investigational doses of H5N1 vaccine formulated with and without
alum adjuvant for use in NIAID-sponsored clinical studies

In Australia:

- A contract has also been signed with the Australian government
for the supply of vaccine in the event of a pandemic influenza
outbreak.

About sanofi-aventis

The sanofi-aventis Group is the world's third-largest
pharmaceutical company, ranking number one in Europe. Backed by a
world-class R&D organization, sanofi-aventis is developing leading
positions in seven major therapeutic areas: cardiovascular disease,
thrombosis, oncology, metabolic diseases, central nervous system,
internal medicine, and vaccines. The sanofi-aventis Group is listed
in Paris (EURONEXT: SAN) and in New York (NYSE: SNY).

sanofi pasteur, the vaccines business of the sanofi-aventis Group,
sold more than a billion doses of vaccine in 2005, making it possible
to protect more than 500 million people across the globe. The company
offers the broadest range of vaccines, providing protection against
20 bacterial and viral diseases. For more information, please visit:
www.sanofipasteur.com / www.sanofipasteur.us

Forward Looking Statements

This press release contains forward-looking statements as defined
in the Private Securities Litigation Reform Act of 1995.
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 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 "expect," "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 sanofi-aventis' annual report on Form 20-F for the
year ended December 31, 2005. 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] Bresson JL, Perronne C, Launay O, et al. Safety and
immunogenicity of an inactivated split-virion influenza
A/Vietnam/1194/2004 (H5N1) vaccine: phase I randomised trial. Lancet
2006 May 20;367(9523):1657-64.

[2] www.who.int/csr/disease/avian_influenza/guidelines/recommendat
ionvaccine.pdf

[3] Treanor JJ, Campbell JD, Zangwill KM, Rowe T, Wolff M. Safety
and immunogenicity of an inactivated subvirion influenza A (H5N1)
vaccine. N Engl J Med 2006 Mar 30;354(13):1343-51.

sanofi pasteur
Alain Bernal
Vice-President Corporate Communications
Tel: + 33-(0)4-37-37-78-97
Fax: +33-(0)4-37-37-77 89
Len Lavenda
U.S. Media Relations
Tel: +1-570-839-4446
Len.Lavenda@sanofipasteur.com

ots Originaltext: sanofi-aventis Group
Im Internet recherchierbar: http://www.presseportal.de

Contact:
sanofi pasteur, Alain Bernal, Vice-President Corporate
Communications,
Tel: + 33-(0)4-37-37-78-97, Fax: +33-(0)4-37-37-77 89; Len Lavenda,
U.S. Media Relations
Tel: +1-570-839-4446, Len.Lavenda@sanofipasteur.com