ATLANTA?The Centers for Disease Control and Prevention has vaccinated some of its health workers against smallpox as a precaution in case they need to investigate a terrorist attack involving the deadly virus, a spokesman said Sunday.

While the CDC has no evidence that anyone is readying a terrorist attack using smallpox, which was eradicated outside laboratories 21 years ago, officials of the federal agency say the virus is so dangerous that it is important they be prepared.

“We are putting together several teams that could be quickly dispatched to the field if we did see a suspected case of smallpox,” CDC spokesman Tom Skinner said Sunday.

The agency expects a number of false alarms as doctors heighten their suspicion of anthrax, smallpox and other diseases, said Dr. Jeffrey Koplan, the CDC director.

Skinner said the CDC is not calling for public vaccinations now.