Three Florida health care workers inoculated against smallpox as part of the Bush administration's bioterrorism preparations have experienced serious side effects that may be linked to the vaccine, federal officials announced yesterday.

Nationwide, two dozen people have reported complications associated with the vaccine, though none has been life-threatening, according to the Centers for Disease Control and Prevention.

A 39-year-old Florida nurse, after complaining of headaches and malaise, developed a severe rash called "generalized vaccinia" that is a known side effect of the inoculation. Although additional testing is being done, health officials expressed confidence that the pustules on her chest and back were caused by the live virus vaccine. She was treated with antihistamines, and doctors do not expect her to have permanent scarring, said Eric Mast, an immunization specialist at CDC.

The two other Florida cases involved symptoms not typically associated with smallpox vaccination -- angina, or severe chest pain, and gallbladder inflammation. Both patients were treated at local hospitals and are in good condition, officials said.

"Although two of the individuals appear to have suffered ailments that have no previously known association with smallpox vaccine, it has been several decades since individuals were vaccinated against smallpox, and we must therefore report on even the most unlikely associated clinical events," said John O. Agwunobi, secretary of the Florida Department of Health.

Health officials have expected a small number of complications associated with the inoculations. In the past, between 14 and 52 of every 1 million people immunized suffered life-threatening side effects such as encephalitis. More common reactions include fever, itching, lethargy and headache.

As of Feb. 21, 7,354 people had been immunized in the voluntary program, designed to vaccinate 500,000 health care workers who would respond to an initial outbreak and open mass vaccination clinics.

More than 108,000 military personnel have been inoculated in the past six weeks, with six serious complications reported, according to the most recent data available from the Pentagon. They included two cases of encephalitis, two serious rashes, one case of myocarditis (inflammation of the heart) and an eye infection.

After studying the CDC figures, the military data and the recent immunization campaign in Israel, Alan Zelicoff, a senior scientist at Sandia National Laboratories has concluded that "the experience to date has been completely consistent with the vaccination experience in the 1960s."

Florida has immunized almost 1,200 people and is checking each of them daily for side effects, said Health Department spokesman Rob Hayes. "We are doing aggressive monitoring," he said, speculating that such an approach may explain why that state has detected the three possible adverse reactions.

All three Floridians missed work because of their symptoms, though officials could not say how much time off they needed or whether they have insurance coverage. The insurance issue has become a major hurdle for the program. State health departments, unions and hospitals say that without a compensation program to cover treatment of side effects and lost work time, it will be difficult to recruit the more than 10 million volunteers for which President Bush asked in December.

"This event reaffirms the need for a compensation program to support health care workers and their contacts injured by the smallpox vaccine," said Rep. Henry A. Waxman (D-Calif.), who has filed legislation that would provide no-fault compensation for anyone harmed in the immunization campaign.

"The president has asked health care workers to volunteer to be immunized so that they can serve society," Waxman said. "In turn, society should help them if they are hurt when they volunteer."

Two sources said the administration is considering a special designation for vaccination volunteers that would entitle them to certain disability or death benefits similar to those provided police officers injured in the line of duty under a 1968 law.