While much of the U.S. public has balked at starting a smallpox vaccination program, the military said yesterday it has vaccinated more than 100,000 troops with just three serious "adverse events."

Two soldiers developed encephalitis, a potentially life-threatening brain inflammation, but both recovered fully, Col. John Grabenstein of the U.S. Army Surgeon General's office said.

An airman developed an even rarer side effect called myocarditis, an inflammation of the heart that can sometimes lead to heart failure, but also recovered, Grabenstein said at a meeting of the Institute of Medicine.

"Even our most severe cases have had a full recovery," Grabenstein said. No one has refused inoculation with the vaccine, he said.

Smallpox was eradicated in 1979, but experts believe groups and governments such as Iraq's may have developed the virus for use as a weapon. President Bush decided the risk was big enough to make it worth vaccinating 450,000 workers so they will be ready to vaccinate others in case of an attack. In addition, 500,000 troops are being vaccinated.

Joe Henderson, associate director for terrorism preparedness at the Centers for Disease Control and Prevention, said 1,043 health and emergency workers had been vaccinated as of Feb. 11, and he expected 45 states as well as the cities of New York, Los Angeles and Washington to have begun vaccinating volunteers by Feb. 21.

The plan is under fire from unions and other groups worried about who will take care of workers made sick by the vaccine.