Trial To Test New Smallpox Vaccine
Researchers will be running tests to compare an established smallpox vaccine against a newer one that may offer fewer side effects.
The question is which will provide the best and quickest protection against a possible terrorist attack using the smallpox virus.
Although the World Health Assembly declared that smallpox was officially eradicated as a disease in 1980, stockpiles of the virus may exist and worries remain that they may fall into the hands of terrorists.
Smallpox is a highly contagious disease that causes fever, malaise and severe rash and kills about 30 percent of people infected. There is no effective treatment, said Chip Walter, M.D., who is directing Duke's effort in the trial, which is sponsored by the National Institute of Allergy and Infectious Diseases, part of the National Institutes of Health.
"It is important that we be as prepared as possible for a bioterrorist attack," Walter said. "There are still concerns that there could be groups who have access to the virus with the intent to harm others. Although the probability of release of smallpox through a terrorist attack is low, the effect could be devastating, since much of the population has not been protected through vaccination."
If a terrorist were to unleash the virus, the goal would be to vaccinate people in the areas closest to the attack, as well as first responders such as ambulance crews and emergency room staff. For this reason, the time it takes a vaccine to provide immunity is crucial, Walter said.
The trial, which begins this month, will compare various doses, combinations and dosing schedules of the two vaccines to determine which can stimulate an effective immune response to the virus in the least amount of the time.
The established vaccine, called Dryvax, has been used for decades, but it has rare and serious complications in some individuals, such as severe skin rashes and inflammation of the heart and brain. It is the vaccine given to U.S. soldiers in the Middle East.
The newer vaccine, called Imvamune, appears to lead to a good immune response with fewer side effects. But being new, little is known about the dosing schedule that will lead to the most rapid immune response.
In the trial, researchers will periodically test blood samples from participants to determine what types of immune responses the vaccines and their combinations are stimulating and to monitor for side effects. Duke plans to enroll 30 healthy volunteers who were born after 1971 and who have not been previously vaccinated against smallpox.
"The results of the trial will help us determine the best and safest approach to achieving protection in the event of a bioterrorism attack using smallpox," Walter said.