Smallpox Vaccine Trial Results

Smallpox vaccine trial resultsCambridge, UK and Cambridge, Massachusetts - 3 September 2002 - Acambis plc("Acambis") (LSE: ACM, NASDAQ: ACAM) announces that it has completed a PhaseI trial of its smallpox vaccine, ACAM1000. The trial tested the safety, tolerability and immunogenicity of ACAM1000 andDryvax®, the smallpox vaccine that was widely used during the worldwidesmallpox eradication programme. In the 60-subject, randomised, double-blindtrial, 30 subjects were given the standard dose of Dryvax® and 30 were givenan equivalent dose of ACAM1000. The currently accepted indication of protective immunogenicity in the caseof smallpox vaccination is the development of a pock-mark on the skin, knownas a "take". This was the primary endpoint of the trial. A "take" was seenwithin 10 days after vaccination in 100% of ACAM1000-treated subjects and97% of Dryvax®-treated subjects. The size and appearance of the "takes"were identical across treatment groups. No serious or unexpected adverseevents were reported in the ACAM1000 group, whereas one subject in theDryvax® group developed a non-healing pock at the site of inoculation. The results of this Phase I trial will be presented by Dr Thomas Monath,Chief Scientific Officer, at a meeting of the G7 Global Health SecurityAction Group being held at the Paul-Ehrlich-Institut in Langen, Germany on5-6 September.Following these encouraging results, a second, open-label trial has beeninitiated in which 70 subjects are being given ACAM1000 to test further thevaccine's safety and immunogenicity. Results from this second trial areexpected to be available shortly.