esponding to increasing concerns about bioterrorism, the company making a smallpox vaccine is sharply accelerating production and now plans to deliver 40 million doses to the federal government next year, a spokesman for the health and human services secretary, Tommy Thompson, said yesterday.

Acambis (news/quote), a company in Cambridge, Mass., had previously said it would deliver the vaccine in 2004.

Kevin Keane, a spokesman for Mr. Thompson, said that government officials began meeting with company officials soon after terrorists attacked New York and Washington on Sept. 11 to determine how the 40 million doses could be manufactured more quickly. The discussions included officials from the Food and Drug Administration, which regulates what testing must be done before a vaccine can be used.

Mr. Keane said it was agreed that some tests and development procedures could be done simultaneously so that the vaccine could be delivered as early as the middle of next year.

The vaccine will be placed in a national stockpile that could be quickly drawn from in case of an attack that infected people with the smallpox virus. Experts say that such an attack is unlikely but possible.