Statement re HIV smallpox vaccine study

    Statement re HIV smallpox vaccine study

Cambridge, UK and Cambridge, Massachusetts - 12 September 2003 - Acambis plc
("Acambis") (LSE: ACM, NASDAQ: ACAM) notes yesterday's announcement by George
Mason University (GMU) reporting preliminary findings from a study that
indicate smallpox vaccination may confer a measurable degree of immunity to HIV
infection.

Recognising that these are early data, Acambis considers these findings to be
very interesting and that they warrant further investigation. Acambis has
collaborated with GMU to review these data and is aware that these findings
have been discussed with a number of key experts in this field. Discussions are
ongoing with GMU concerning collaborative work to corroborate the data they
have produced.

Acambis is recognised as the world's leading producer of smallpox vaccines. It
is supplying governments around the world with emergency-use stockpiles of a
new second-generation smallpox vaccine to counter the threat of smallpox being
used as a biological weapon.

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Enquiries:

Acambis plc                                                                    
                                                                               
Dr John Brown, Chief Executive Officer   Tel: [phone]             
                                                                               
Lyndsay Wright, Director of                                                    
Communications                                                                 
                                                                               
Gordon Cameron, Chief Financial Officer  Tel: [phone]                
                                                                               
Financial Dynamics                                                             
                                                                               
David Yates/Jonathan Birt                Tel: [phone]             

Notes to editors:

Acambis is a leading developer of vaccines to prevent and treat infectious
diseases. Recognised internationally as the leading producer of smallpox
vaccines, Acambis provides governments around the world with the full portfolio
of related smallpox vaccine products required to protect their citizens against
the threat of smallpox virus being used as a bioterrorist weapon. Acambis is
establishing a travel vaccines franchise, including vaccines against yellow
fever, Japanese encephalitis, dengue fever and typhoid. Acambis also has the
most advanced vaccine in development targeting the West Nile virus, which has
spread to over 40 US States in the last three 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.



END