Acambis files US licence application for ARILVAX yellow fever vaccine

Cambridge, UK and Cambridge, Massachusetts - 12 December 2003 - Acambis plc
("Acambis") (LSE: ACM, NASDAQ: ACAM) announces that it has filed a Biologics
License Application ("BLA") with the CBER vaccine division of the US Food and
Drug Administration ("FDA") to seek registration in the US of its ARILVAXTM
vaccine to prevent yellow fever.

Acambis recently completed a Phase III paediatric trial of ARILVAXTM, which
provided additional data to supplement that generated from two previous Phase
III adult trials.

ARILVAXTM is a live, attenuated vaccine to prevent yellow fever. It is already
registered in 10 countries, including the UK, and Acambis has the rights to
market the vaccine in the US. Rights outside of the US are owned by the
vaccine's manufacturer, Chiron Vaccines, part of California-based Chiron
Corporation.

Dr John Brown, Chief Executive Officer of Acambis, commented:

"This submission marks a major achievement for Acambis, not only because this
is our first ever BLA but also because it is the first time a BLA has been
submitted electronically to the CBER vaccine division of the FDA. It is another
significant milestone in our plan to establish a travel vaccines franchise in
North America."

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Enquiries:

Acambis plc                                                                    
                                                                               
Dr John Brown, Chief Executive Officer   Tel: +44 (0) 1223 275 300             
                                                                               
Lyndsay Wright, Director of                                                    
Communications                                                                 
                                                                               
Gordon Cameron, Chief Financial Officer  Tel: +1 (617) 761 4200                
                                                                               
Financial Dynamics                                                             
                                                                               
David Yates/ Charlie Armitstead          Tel: +44 (0) 20 7831 3113             

About Acambis

Acambis is a leading developer of vaccines to prevent and treat infectious
diseases. Recognised internationally as the leading producer of smallpox
vaccines, Acambis is developing a second-generation smallpox vaccine which is
currently undergoing clinical trials and, under a unique arrangement given the
threat of smallpox being used as a bioterrorist weapon, is manufacturing
emergency-use stockpiles of this investigational vaccine for the US Government
and other governments around the world. Acambis is establishing a travel
vaccines franchise through its US-based subsidiary Berna Products Corporation,
which markets Vivotif�, the world's only oral typhoid vaccine, in North
America. Acambis has a number of other potential travel vaccines in development
and is conducting clinical trials of vaccines against yellow fever, Japanese
encephalitis and dengue fever. Acambis recently became the first company to
start human clinical trials of a vaccine targeting the West Nile virus, which
has spread to 45 US States in the last four years.

Acambis is based in Cambridge, UK and Cambridge, Massachusetts, US. Its primary
listing is on the London Stock Exchange (ACM) and its shares are listed in the
form of American Depositary Receipts on Nasdaq (ACAM). More information is
available at www.acambis.com.

"Safe Harbor" statement under the Private Securities Litigation Reform Act of
1995:

The statements in this news release that are not historical facts are
forward-looking statements that involve risks and uncertainties, including the
timing and results of clinical trials, product development, manufacturing and
commercialisation risks, the risks of satisfying the regulatory approval
process in a timely manner, the need for and the availability of additional
capital. For a discussion of these and other risks and uncertainties see "Risk
factors" in the Company's Annual Report and Form 20-F for the most recently
ended fiscal year, in addition to those detailed in the Company's filings made
with the Securities and Exchange Commission from time to time. These
forward-looking statements are based on estimates and assumptions made by the
management of Acambis and are believed to be reasonable, though are inherently
uncertain and difficult to predict. Actual results or experience could differ
materially from the forward-looking statements.



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