The plan offers instructions for how to vaccinate the U.S. population within days should it become necessary. No decisions have been made, though, about the circumstances under which those plans would be activated, officials said.
The highly contagious disease has not been seen in this country for decades and routine vaccinations ended in 1971. It was declared eradicated in 1980, and routine smallpox vaccination stopped in the United States in 1972. The United States and Russia keep the only official supplies of the variola virus that causes smallpox, but experts fear other countries or extremist groups may have access to the agent and could unleash it as a biological weapon.
The new blueprint does not address a much thornier issue now under intense discussion within the Bush administration: whom to vaccinate before an attack even occurs. A decision on that issue is expected by the end of the month.
Rather, the state planning guide addresses mass vaccinations after smallpox is discovered. It goes well beyond earlier planning, which has revolved around "ring vaccination," where authorities deliver shots first to those closest to the contagious patient.
Under ring vaccination, health officials work away from the central smallpox patient in concentric circles, delivering shots to people the patient may have exposed and then to others who those people may have exposed.
Mass vaccination is a much more aggressive approach and officials believe it could be necessary in order to halt a fast-spreading smallpox virus.
The smallpox vaccine offers protection against the disease even if administered after someone is exposed, as long as they get the shot within a few days.
The logistics of vaccinating large numbers of people all at once are exceedingly complicated. The plan being sent Monday, nearly 100 pages long, addresses "anything you can think of in running a vaccine clinic," one federal official said Sunday, speaking on condition of anonymity.
"It literally says, 'here's how you set one up and here's how you run it,'" the official said.
"This is a very detailed, thoughtful recipe for response" to a bioterror incident, said Michael Osterholm, a public health expert at the University of Minnesota who is advising the federal government.
Specific questions addressed include how many clinics and health care workers would be needed, where the clinics should be stationed and how to deal with the news media. The plan also addresses security issues including how to keep order among an anxious public.
Federal health officials are also in the final stages of planning for who to vaccinate in the short term, absent a smallpox case.
The vaccine carries significant risks, including death, leaving officials to balance the risk of the side effects against the risk of the disease's return.
The highly contagious disease is characterized by blistering of the skin and fever, and kills about 30 percent of its victims.
Officials at the White House and the Department of Health and Human Services are nearing a final decision on whom to vaccinate right away.
They have settled on a staged approach, beginning with health care workers and emergency responders who face the greatest risk of seeing a contagious smallpox patient.
Then, they plan to offer the vaccine to others, such as other health care workers and emergency responders, officials have said.
They are considering a final stage where the vaccine would be offered to everyone in the country, though one official said Sunday that no final decision had been made on that issue.