LOUISVILLE - The federal Centers for Disease Control and Prevention has approved the state's plan for distributing smallpox vaccinations to as many as 8,000 public health and hospital workers, state officials said.

The vaccinations, ordered by President Bush as part of an effort to prepare for a potential bioterrorism attack, are expected to begin some time after Jan. 24, when the Homeland Security Act is effective.

Inoculations will be offered to hospital employees and doctors who would treat the first smallpox victims, public health workers and officials who would investigate outbreaks and those charged with giving vaccinations, said Rice Leach, commissioner for the Kentucky Department for Public Health.

Vaccinations will be conducted at 10 health department facilities across the state, including sites in Louisville and Lexington.

The process should take 30 to 45 days, said Doug Thoroughman, a CDC epidemiologist assigned to Kentucky.

The inoculations are voluntary. It will be up to health-care workers to decide whether the chance of a bioterrorism attack is greater than the chance of suffering potentially dangerous side effects from the vaccine.

The vaccine, which is made from a live virus distantly related to smallpox, is designed to cause a small skin infection around the inoculation site. In most cases, it causes a blister and soreness. But some recipients will develop flu-like symptoms.

Severe, life-threatening reactions occur in 14 to 52 of every 1 million Americans who were vaccinated before 1972, when routine inoculations for smallpox ended in the United States.

One or two of every 1 million recipients who were vaccinated before 1972 died.

Leach said a hospital in New York and one in Atlanta have declined to provide the vaccinations on the basis that the threat doesn't warrant the risks.

Officials said they think most or all Kentucky hospitals will offer the vaccine, despite an initial survey conducted about six weeks ago found that 16 of 84 hospitals said they weren't certain whether they would pre-vaccinate employees. Most wanted more information, he said.

"A lot of folks were weary about this," Dr. Thoroughman said.

The last case of smallpox in the United States was in 1949. Worldwide, smallpox was eradicated in 1977.

But the Bush administration believes that Iraq and some other nations may have stockpiles of the virus.