Official: Threat of smallpox bioterrorism real

WASHINGTON (CNN) -- The threat of smallpox as a bioterrorist weapon is real and health officials are doing everything they can to "keep the citizens of our nation safe" from such an attack, the head of the National Institutes of Health said Friday.

A smallpox attack is just one of many potential bioterrorism threats, but "perhaps it is the most frightening," said Dr. Anthony Fauci, director of the NIH.

"It's a virus that's easily transmitted from person to person through aerosolized droplets from saliva and other body fluids," said Fauci, speaking before a Senate panel. "It is unlike anthrax in that it can be transmitted from person to person and not just a danger by a direct contact."

Smallpox, a highly contagious virus that kills at least 30 percent of its victims and disfigures many who survive, was eradicated from the globe more than two decades ago. Scientists retained stocks of the variola virus, which causes tjhe disease, and stored them in secure laboratories in Atlanta, Georgia, and Moscow, Russia.

"There are other possibilities that stores (of smallpox) may exist outside of those locations," Fauci said. "So the threat of the use of smallpox as a bioterrorist weapon is real."

Health officials are working to stockpile vaccines and prepare local officials for a potential attack, he said.

"The NIH is committed to focusing its basic and clinical research efforts to approach and hopefully overcome this bioterrorism threat," Fauci said.

The United States has 15 million doses of smallpox vaccine on hand, but Fauci said officials are investigating whether those vaccines can be safely diluted to make more -- what he called a "short-term amelioration of the shortage response."

If diluting the current stockpile worked, it would increase the supply five-fold to about 75 million doses, Fauci estimated.

Researchers at four medical centers are using 684 volunteers to see if the smallpox vaccine stockpile can be diluted by five times or 10 times its current dosage, Fauci said.

"We'll use those different strengths to vaccinate people to see how often they have a response or take to the vaccine," Dr. Sharon Frey with the Center for Vaccine Development at St. Louis University told CNN.

Researchers will know if the vaccine works if a characteristic scab forms at the injection site after six to 10 days.

Health officials also are negotiating with vaccine makers to speed up a new, second generation vaccine that would give the nation 300 million doses by next year -- enough for every man, woman and child in the United States.

But the vaccine is not without its risks: Between one and six patients per million die from the shot, Fauci said. "It's extremely conceivable we will have to accept those risks and vaccinate people," Fauci said.

One lingering question remains: Is the vaccine administered to millions of Americans years ago still effective against?

"People who were vaccinated many decades ago are probably partially protected, but not completely protected against smallpox," said Dr. Robert Belshe, the director of the research center at St. Louis University.

Symptoms of smallpox typically appear about 12 days after infection and include high fever, fatigue, and head and back pain. A characteristic rash also appears about two or three days later on the face, arms and legs. The rash starts with flat red lesions, but then become pus-filled and begins to crust in the second week.