Genzyme, a Sanofi company (EURONEXT: SAN and NYSE: SNY), today announced that due to the continued progress in its manufacturing operations this year, its supply of Thyrogen ® (thyrotropin alfa for injection) has been fully restored. As a result, beginning in November, Genzyme is able to supply all patient demand globally. “We are grateful to the Thyroid cancer treatment community for its ongoing patience and partnership,” said Genzyme’s Vice President and General Manager of Endocrinology, Alicia Secor. “Genzyme continues to invest in our manufacturing capabilities and we are dedicated to delivering high quality product and continuous supply of Thyrogen for the long term.” Health care providers should acquire Thyrogen through normal distribution channels to schedule any new Thyrogen treatments. About Thyrogen Thyrogen (thyrotropin alfa for injection) is for patients with well-differentiated thyroid cancer. Thyrogen is approved as an adjunctive diagnostic tool for serum thyroglobulin (Tg) testing with or without radioiodine imaging. Thyrogen is also approved in the U.S. and Europe as an adjunctive treatment for radioiodine ablation of thyroid tissue remnants in patients who have undergone a near total or total thyroidectomy for well-differentiated thyroid cancer and who do not have evidence of metastatic thyroid cancer. About Genzyme, a Sanofi Company Genzyme has pioneered the development and delivery of transformative therapies for patients affected by rare and debilitating diseases for over 30 years. We accomplish our goals through world-class research and with the compassion and commitment of our employees. With a focus on rare diseases and multiple sclerosis, we are dedicated to making a positive impact on the lives of the patients and families we serve. That goal guides and inspires us every day. Genzyme’s portfolio of transformative therapies, which are marketed in countries around the world, represents groundbreaking and life-saving advances in medicine. As a Sanofi company, Genzyme benefits from the reach and resources of one of the world’s largest pharmaceutical companies, with a shared commitment to improving the lives of patients. Learn more at www.genzyme.com. Genzyme ® and Thyrogen ® are registered trademarks of Genzyme Corporation. All rights reserved. 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 projections and estimates and their underlying assumptions, statements regarding plans, objectives, intentions and expectations with respect to future financial results, events, operations, services, product development and potential, 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’s 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, 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 among other things, the uncertainties inherent in research and development, future clinical data and analysis, including post marketing, decisions by regulatory authorities, such as the FDA or the EMA, regarding whether and when to approve any drug, device or biological application that may be filed for any such product candidates as well as their decisions regarding labeling and other matters that could affect the availability or commercial potential of such products candidates, the absence of guarantee that the products candidates if approved will be commercially successful, the future approval and commercial success of therapeutic alternatives, the Group’s ability to benefit from external growth opportunities as well as those discussed or identified in the public filings with the SEC and the AMF made by Sanofi, including those listed under “Risk Factors” and “Cautionary Statement Regarding Forward-Looking Statements” in Sanofi’s annual report on Form 20-F for the year ended December 31, 2010. Other than as required by applicable law, Sanofi does not undertake any obligation to update or revise any forward-looking information or statements.