Shares in UK biotechnology firm Acambis have risen after a review ahead of an advisory meeting in the USA made positive noises about the efficacy of the firm’s new smallpox vaccine.

Staff at the US Food and Drug Administration, speaking ahead of an advisory meeting at the agency on Thursday, said that data from studies of the company’s ACAM2000 vaccine showed it is non-inferior to Wyeth’s now-discontinued smallpox vaccine Dryvax, from which it is derived, while efficacy was demonstrated in two Phase III clinical trials in that it generated major cutaneous reaction and serum neutralising antibody.

The USA has already stockpiled 192.5 million doses of the vaccine, according to its manufacturer, and Acambis anticipates that the vaccine, if approved by the FDA, will be used on deployed military personnel and others at risk of smallpox if there is an outbreak.

The USA ended routine childhood vaccination against smallpox in 1971, but after the terrorist attacks of September 11, 2001, the Bush administration ordered that some military personnel be vaccinated and recommended shots for front-line health care workers. The government since has stockpiled enough smallpox vaccine for everyone in the country.

If approval is forthcoming, this will be a quite a boost for Acambis especially when one remembers how the firm’s stock slumped at the end of last year when the US Department of Health and Human services decided that its tender to provide a weakened version of the vaccine was uncompetitive.