The Defense Department announced Wednesday that it would expand its anthrax and smallpox vaccination programs to include all personnel deployed by U.S. Central Command and, for the first time, select units within U.S. Pacific Command.

Previously, approximately half of deployed personnel had been vaccinated in Central Command, which includes the Afghanistan and Iraq theaters of operation.

"It was probably well over half, but this includes everyone," said William Winkenwerder Jr., assistant secretary of defense for health affairs. "Probably more will be affected in the Pacific Command than in the Central Command," he added, without discussing specific numbers of expected inoculations or a vaccination schedule.

He said this would be the first time U.S. service members on the Korean Peninsula under the Pacific Command would receive the vaccinations.

Winkenwerder said the decision to expand vaccinations was not in response to any specific threat. "There is no substantial change to the threat situation," he said.

The vaccination program would continue to include personnel in selected units assigned or deployed for 15 or more consecutive days, according to Winkenwerder, including essential civilian employees and contractors. The Defense

Department would offer the vaccinations to family members of those personnel on a voluntary basis, as it has done in the past, he added.

He said the decision to expand vaccination came after a periodic review of the program and an evaluation of potential threats.

"When we began these vaccination programs we stated that we would periodically review them, evaluating the threats to our forces and vaccine availability," he said. "We recently completed such an evaluation and determined that the threat continues," he added.

He said the cost of the additional vaccinations would be relatively low and that the necessary doses have already been manufactured and stockpiled.

"Additional costs, we expect, are not substantial. Our total budget is roughly $30 billion, this is in the tens of millions," he said. "Sufficient funds have already been allocated in the 2004 and 2005 budgets," he added.

The Defense Department continues to reserve a portion of the vaccine supply for use by other federal agencies.

"The Office of Homeland Security heads the planning effort among federal agencies for use of the vaccine in case of a domestic emergency," Winkenwerder said.

Anthrax remains one of the top biological warfare threats to U.S. troops, according to Winkenwerder.

"Some of our adversaries, we suspect, possess anthrax," he said.

To date, the Defense Department has vaccinated more than 750,000 service members with more than 2.2 million doses of anthrax vaccine. More than 625,000 service members have received the smallpox vaccine since December 2002, he said.