AVANT Announces Start of Phase I/II Clinical Trial of Its Typhoid Fever Vaccine.

NEEDHAM, Mass. -- AVANT Immunotherapeutics, Inc. (Nasdaq: AVAN) announced today the start of a placebo-controlled, double-blind Phase I/II study of its typhoid fever vaccine candidate, Ty800. The clinical trial, sponsored by the National Institute of Allergy and Infectious Disease (NIAID), a component of the National Institutes of Health (NIH), is being conducted at the Cincinnati Children's Hospital Medical Center.

The Phase I/II study is an in-patient dose-escalating clinical trial aimed at determining the safety and immunogenicity of the single-dose, oral Ty800 vaccine. The trial will evaluate three escalating dose levels of the vaccine, in approximately 54 healthy adult volunteers and will follow each subject for six months post-vaccination. The trial seeks to confirm the safety and immunogenicity of the Ty800 vaccine observed in an earlier physician-sponsored Ty800 vaccine study.

"We are delighted that the NIAID is initiating clinical testing of our single-dose, oral Ty800 vaccine," said Una S. Ryan, President and Chief Executive Officer of AVANT Immunotherapeutics, Inc. "The development of a safe and effective typhoid fever vaccine is important for protecting residents, travelers and military personnel from typhoid fever in endemic areas. We see the initiation of this trial as serving the dual role of addressing a significant health issue in the developing world and advancing development of AVANT's extensive bacterial vaccine franchise. AVANT has also conducted advanced clinical studies of its single-dose, oral cholera vaccine, CholeraGarde(R), and has enterotoxigenic E. coli ETEC, Shigella and Campylobacter vaccines in preclinical development."

AVANT has designed the Ty800 vaccine to offer rapid, oral, single-dose protection against Salmonella typhi, the cause of typhoid fever. The Ty800 vaccine was developed using genetic techniques to delete specific genes known to be essential to the virulence of S. typhi. The clinical trial is designed to show that Ty800 is well tolerated in humans and rapidly elicits strong immune responses.

About AVANT Immunotherapeutics, Inc.

AVANT Immunotherapeutics, Inc. discovers and develops innovative vaccines and therapeutics that harness the human immune system to prevent and treat disease. Six of AVANT's products are in clinical development, including a treatment to reduce complement-mediated tissue damage associated with cardiac bypass surgery and a novel vaccine for cholesterol management. AVANT is also developing a pipeline of bacteria-fighting products for biodefense, travelers' vaccines, and global health needs based on AVANT'S rapid-protecting, single-dose, oral and temperature stable vaccine technology.

Additional information on AVANT Immunotherapeutics, Inc. can be obtained through our site on the World Wide Web: http://www.avantimmune.com.

Safe Harbor Statement Under the Private Securities Litigation Reform Act of 1995:

This release includes forward-looking statements which reflect AVANT's current views with respect to future events and financial performance. These forward-looking statements are based on management's beliefs and assumptions and information currently available. The words "believe", "expect", "anticipate", "intend", "estimate", "project" and similar expressions which do not relate solely to historical matters identify forward-looking statements. Investors should be cautious in relying on forward-looking statements because they are subject to a variety of risks, uncertainties, and other factors that could cause actual results to differ materially from those expressed in any such forward-looking statements. These factors include, but are not limited to: (1) the integration of multiple technologies and programs; (2) the ability to adapt AVANT's vectoring systems to develop new, safe and effective orally administered vaccines against anthrax and plague or other bioterrorism threats or emerging health care threats; (3) the ability to successfully complete development and commercialization of TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other products; (4) the cost, timing, scope and results of ongoing safety and efficacy trials of TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other preclinical and clinical testing; (5) the ability to successfully complete product research and further development, including animal, pre-clinical and clinical studies of TP10, CETi-1, CholeraGarde(R) (Peru-15), Ty800 and other products; (6) the ability of the Company to manage multiple late stage clinical trials for a variety of product candidates; (7) the volume and profitability of product sales of Megan(R)Vac 1, Megan(R)Egg and other future products; (8) the process of obtaining regulatory approval for the sale of Rotarix (R) in major commercial markets, as well as the timing and success of worldwide commercialization of Rotarix (R) by our partner, GlaxoSmithKline; (9) changes in existing and potential relationships with corporate collaborators; (10) the availability, cost, delivery and quality of clinical and commercial grade materials supplied by contract manufacturers; (11) the timing, cost and uncertainty of obtaining regulatory approvals to use TP10, CETi-1, CholeraGarde(R) (Peru-15) and Ty800, among other purposes, for adults undergoing cardiac surgery, to raise serum HDL cholesterol levels and to protect travelers and people in endemic regions from diarrhea causing diseases, respectively; (12) the ability to obtain substantial additional funding; (13) the ability to develop and commercialize products before competitors; (14) the ability to retain certain members of management; and (15) other factors detailed from time to time in filings with the Securities and Exchange Commission. We expressly disclaim any responsibility to update forward-looking statements.