Vaccine study targets those already immunized as children.(against smallpox)

2002 DEC 4 - (NewsRx.com & NewsRx.net) -- Doctors and nurses at the University of Rochester Medical Center have been chosen to lead the largest study of smallpox vaccine to date, a nationwide study of approximately 900 patients that will be conducted at seven sites around the country, including Rochester, New York.

Approximately 200 people in the Rochester area who were vaccinated against the disease as children will receive a booster shot as part of the study. John Treanor, MD, associate professor of medicine and director of the medical center's Vaccine and Treatment Evaluation Unit, will lead the national study, coordinating doctors at all seven sites and guiding the effort to evaluate the results.

Last year, shortly after the September 11 attack, 170 people were vaccinated against smallpox at the university, part of a larger nationwide study which determined that a diluted form of the vaccine could protect people as well as a full dose.

While the previous study looked at adults who had never been vaccinated - nearly everyone born after 1972 - this year's study will focus on adults who were vaccinated as children, to see how a booster shot affects the protection they have against the disease.

As in last year's study, participants will receive either a standard dose of vaccine, one-fifth the standard dose, or one-tenth the standard dose. Doctors and nurses will monitor their immune response and side effects to determine the most effective dose.

"It's important to know which dose works best for this group of people," said Treanor. "This is very similar to the study last year, except now we're looking at people who did receive the vaccine as children. It's crucial to protect this group as well."

Doctors aren't sure just how well such people are currently protected against the disease. While it's known that some diseases, like tetanus, require repeated immunization, the need to administer repeated doses is less clear with smallpox. With the threat of bioterrorism, officials are exploring the issue more thoroughly.