Sen. Arlen Specter, R-Pa., chair of the labor, health and human services subcommittee on education, which held the hearing, stressed the need to try to obtain such intelligence and make it available to the American public.
"We need a better assessment of risk," he said.
"We can't give absolute quantitative risk (but) there is a real possibility of a smallpox attack," responded Dr. Julie Gerberding, director of the Centers for Disease Control and Prevention in Atlanta. "Individual entities (such as terrorist organizations) could have access to smallpox," Gerberding said, adding that some information regarding the risk is classified.
"We're not recommending immunizing the entire country at this point," she added, noting the risk is not sufficient to justify it.
Dr. Anthony Fauci, director of the National Institute on Allergy and Infectious Diseases in Bethesda, Md., said smallpox can be weaponized and has been in the past by experts in the former Soviet Union. But he admitted he does not know whether any country or terrorist organization has such a capability now.
At the time of the dissolution of the Soviet Union in the early 1990s, its scientists were in dire financial situations, Fauci said, adding it is not unreasonable to expect some of those scientists took their knowledge elsewhere.
Although the risks of attack are unclear, he said, the better-defined risks are those involved in administering smallpox vaccinations. Between 14 and 52 people per million could have life-threatening reactions and one to two could die, Fauci said. He noted, however, that risk assessments are based on old data and new developments could change the numbers.
In the age of HIV, organ transplantation and chemotherapy, there are a number of medical procedures that can depress a person's immune system, he explained, making that person more vulnerable to a smallpox infection.
To counter the risks involved, Fauci said NIAID is looking at alternatives to the currently available vaccine. An alternate could pose a lesser risk to children, pregnant women and other people who have depressed immune systems.
In addition, there is something called vaccinia immune globulin that can help fight potential complications of vaccination. Right now, Fauci said there is enough VIG to cover all the smallpox vaccination adverse reactions that have been projected. By summer, there will be enough to cover 300 million vaccinees, he added.
Despite such advances, Dr. Louis Bell, medical director of infection control at the Children's Hospital of Philadelphia, said, "the Children's Hospital does not recommend vaccination for front-line health care workers at our institution because of the vulnerable population we serve."
The children treated at the Philadelphia facility could be at a high risk of being infected if they come in contact with vaccinated health care workers, Bell testified. At this point, Bell said he does not see the justification for a vaccination program at the Children's Hospital.
James August, director of health and safety at the American Federation of State County and Municipal Employees, agreed the vaccination program should be delayed, though for different reasons.
The union wants guarantees that workers will be educated on the vaccination and its risks and that they will compensated for any adverse reactions that could occur as a result of vaccination, August told senators.
August also listed as prerequisites to vaccination guarantees workers will not be pressured into taking the vaccination, they will not suffer repercussions if they choose not to participate and funds will not be diverted from other programs to fund the smallpox vaccination program.
Others agreed the lack of compensation and diversion of funds were major issues.
Dr. Brian Strom, chair of the Institute of Medicine's committee on smallpox vaccination, said lack of compensation for adverse events could jeopardize overall progress.
Another risk of the smallpox program is paying too much attention to one possible bioterror disease.
"Focus has changed from broad preparedness to smallpox preparedness," said Jane Colacecchi, interim director of the Iowa Department of Public Health in Des Moines.
The shift has damaged other aspects of bioterrorism preparedness and unrelated programs such as prevention of sexually transmitted diseases, Colacecchi said.
Although Fauci warned that the country is not prepared for an attack by all of the microbes on a list of potential agents -- including botulism, ebola and plague -- he said researchers are working to develop vaccines to improve readiness.
A discussion of costs of such programs brought estimates ranging from $10 per vaccination by the CDC to $400 by the IDPH.
"We don't really know what this will cost," Gerberding commented.
With the money already set aside for the smallpox vaccination program, Gerberding said a number of programs have started moving forward. Steps are being taken to educate health care workers, enough vaccine is available to immunize the entire country, and research is moving toward the very early detection of attack, she said.