LEXINGTON, Ky. (AP) -- University of Kentucky researchers are studying the safety of a new smallpox vaccine as part of a national program to develop medications that would protect U.S. citizens against a terrorist attack involving biological agents.

The study is being conducted at 11 sites in the U.S. and Mexico, but it doesn’t involve the smallpox virus, which is highly contagious and was eradicated through vaccination.

Unlike the current vaccine, which leaves a pocklike scar, the prospective one called Imvamune is injected. It contains a non-replicating version of the vaccinia virus, which scientists believe will make it safer than the current vaccine.

The study is examining how people who have chronic inflammatory skin conditions such as eczema react to the new medication.

“It’s going to help the United States and the world,” said Dr. Richard Greenberg, who studies infectious diseases and is leading the research at the University of Kentucky.

The current vaccine delivers the live virus vaccinia with a series of pricks. It can cause serious, even life-threatening conditions in people with atopic dermatitis, as the skin conditions are called. The new vaccine contains a version of vaccinia developed in Germany.

The U.S. government stepped up its vaccination research program after the Sept. 11, 2001, terrorist attacks, even though the last U.S. case of smallpox was in 1949 and the last reported case anywhere was in 1977 in Somalia.

Civilian immunization against the disease in the U.S. stopped in 1972, although soldiers are now vaccinated.

The Centers for Disease Control and Prevention estimates that for every 1 million people vaccinated, one or two may die and others will have serious side effects.

In the study of the new vaccine, healthy volunteers, those with atopic dermatitis, and those with a history of atopic dermatitis will be vaccinated. Their immune reaction will be measured through blood tests, and side effects will be tracked in a journal.

Because smallpox no longer exists naturally, scientists have no way of proving that a vaccine like Imvamune works in humans. They can only measure the immune response.

“It’s a reasonable leap of faith, but it’s a leap of faith,” Greenberg said.

Information from: Lexington Herald-Leader, http://www.kentucky.com

(Copyright 2008 by The Associated Press.  All Rights Reserved.)