Duke medical researchers are participating in a study that could have profound implications for the United States as it wages its ongoing war on terrorism.

The nationwide study will aim to determine whether adults who received smallpox vaccinations before 1972 can renew their immunity with a diluted booster vaccine. Duke's study is part of a trial sponsored by the National Institute of Allergy and Infectious Diseases of the National Institutes of Health that includes the University of California at Los Angeles, the University of Maryland, Stanford University and three other institutions.

The study will involve 927 people nationally, and Duke will administer doses to about 90 people between the ages of 32 and 70. The participants will be given a full-strength vaccine or a diluted version at either 10 percent or 20 percent of the vaccine's full strength. The volunteers will then be monitored for reactions that indicate their level of immunity as well as side effects.

"We are in the process of recruiting," said Dr. Emmanuel Walter, associate director of the Primary Care Research Consortium of the Duke Clinical Research Institute and the leader of the Duke study. "We plan to start vaccination sometime next week. We're trying to recruit in the next month and will be done recruiting by early February, and then we'll be following patients for six months."

Dr. John Treanor, associate professor of medicine at the University of Rochester and leader of the seven-school study, said that when subjects receive the smallpox vaccination, the agent has to replicate in order to generate an immune response.

"The process of growing in the skin creates a large pus-filled pimple to develop on the arm," he said. "It's been pretty well established through observations that if you respond to vaccination by developing this pustule, you'll be vaccinated against smallpox."

Walter added that the researchers would use blood tests to confirm the presence of smallpox antibodies.

Treanor noted that an even greater benefit of the study may be learning about the vaccine's effects.

"By doing these studies, we're learning a lot about the different behavior of smallpox vaccine in different people," he said. "It is useful because it gives people experience that could make [a possible mass vaccination] process go more smoothly."

Walter said the study will monitor safety and side effects in patients as well and that the study will be somewhat of a reeducation process for him and his colleagues.

"In my lifetime, I haven't had a lot of experience with the vaccine, so we'll be monitoring that," he said.

The federal government now has 15 million doses of an old vaccine that has been tested by the Food and Drug Administration, but has ordered another 209 million doses of a newer vaccine. As the vaccine causes fatal side effects in one to two cases per million, the new government vaccination campaign has been criticized.

The worldwide eradication of smallpox by the World Health Organization in 1980 has been hailed as a major public health triumph of the 20th century, but experts have increasingly feared that terrorist groups could obtain samples of the virus from research laboratories and use it as a bioterrorist agent.

Routine vaccination ended in 1972 in the United States, and many people who received the vaccine no longer have immunity and would therefore not be protected against a smallpox outbreak.

As the existing supply would not be large enough to treat the entire U.S. population, the results of the study could allow the supply to be stretched by a factor of five or 10 times.

Smallpox is a highly contagious virus that causes fever and a rash and has about a 30 percent fatality rate. No known effective treatment for the disease exists.

Duke will begin screening potential study volunteers this month. Individuals interested in participating in the study should call 668-8627.