CBS News reported Wednesday night that the federal government had done an "about-face" and was now allowing states to suspend or stop vaccinating civilians against the deadly virus, which has been eradicated but is a highly feared weapon of bioterrorism.

Administration officials say states have always had the option of how to run their end of the program with the controversial and potentially harmful vaccine.

"U.S. policy has not changed since we announced it in December of 2002," says Bill Pierce, a spokesman for the Department of Health and Human Services (HHS). "The program has always been voluntary, with our guidance."

So far, Pierce adds, no state has bowed out of the plan. However, some hospitals and individuals have declined to participate. And several states have suspended their vaccination programs in response to concerns over heart-related side effects from the inoculation.

When it announced the vaccine policy late last year, the U.S. government called for a two-phase, voluntary strategy for civilians. In the first stage, roughly 450,000 health-care and emergency workers would receive the vaccine, followed by a second round covering up to 10 million other so-called "first responders" in the event of a bioterror attack with the virus.

At the time, HHS Secretary Tommy Thompson said he expected states to proceed quickly between the two phases. However, an independent advisory panel has consistently urged that states pause to evaluate the safety of the vaccine, which can cause deadly reactions in rare cases.

"Our feeling was it was very important that there be a pause between phase one and phase two to learn from the experience," says Dr. Brian Strom, head of the Institute of Medicine panel advising the federal government on the smallpox vaccine plan.

"Our recommendation is that the length of the pause be determined by data rather than by an arbitrary time frame," adds Strom, of the University of Pennsylvania School of Medicine.

Between Jan. 24 and the last week of April, 34,541 civilian health workers voluntarily received the smallpox vaccine, far fewer than the number officials had projected.

The government has received 55 reports of serious adverse reactions to the smallpox vaccine among civilians and is investigating at least three heart attack deaths -- two civilian and one military -- possibly linked to the inoculation. The vaccine has also caused 413 cases of mild complications, such as fevers, rashes and headaches, according to a report in the May 9 Morbidity and Mortality Weekly Report, which was released Thursday by the CDC.

Of the serious problems among civilians who received the vaccine, 15 involved myopericarditis, a potentially life-threatening heart inflammation. Another 17 cases of the inflammation had been identified in soldiers through late last month, Strom says.

More information

Learn about smallpox and the vaccination from the Centers for Disease Control and Prevention or the Department of Defense.