Acambis is celebrating the news that the US Food and Drug Administration has approved a smallpox vaccine made by the UK firm which will form part of a government stockpile to be used in case of a biological attack.

ACAM2000 is a second-generation smallpox vaccine which is derived from a clone of Dryvax, licensed by the FDA from Wyeth as far back as 1931 and grown on the skin of calves and freeze-dried for storage. It is no longer manufactured and remaining supplies are limited. Now, “the licensure of ACAM2000 supplements our current supply of smallpox vaccine, meaning we are more prepared to protect the population should the virus ever be used as a weapon," said Jesse Goodman, director of FDA's Center for Biologics Evaluation and Research.

The approval for ACAM2000, which is produced using modern cell culture technology, is based on a clinical study demonstrating its non-inferiority to Dryvax, although the FDA noted that about one in 175 healthy adults who received the vaccine for the first time developed myocarditis and/or pericarditis, though there were no fatalities.

The US Centers for Disease Control and Prevention already has stockpiled 192.5 million doses of the vaccine, under a deal signed in 2001 with Acambis, and the FDA noted that the vaccine will not be available to the public commercially, but rather military personnel and laboratory researchers working on certain pox viruses.

The approval is good news for Acambis as the FDA’s green light was necessary for the firm to be able to compete for other stockpile contracts. At the end of last year, the firm, and US partner Baxter, were informed by the US Department of Health and Human Services that their tender to supply a modified vaccinia Ankara (MVA) vaccine was “uncompetitive”, and they lost out to rival Bavarian Nordic