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By SARA SELIS Medical center researchers are conducting a clinical trial that will test whether diluted doses of the smallpox vaccine will produce an adequate response in adults who have previously been vaccinated. The results of the federally funded study, for which volunteers are now being sought, will help shape U.S. policy on how the vaccine would be given in the event of a smallpox outbreak. Smallpox is a highly contagious viral disease that proves fatal to about 30 percent of its victims. Routine vaccination was stopped in the United States in 1971, and smallpox was declared eradicated worldwide in 1980. Ever since last fall’s anthrax attacks on the East Coast, however, smallpox has been considered a likely candidate for use in biowarfare, and there has been strong interest in determining how the United States could best protect its population in case of a smallpox attack.
Cornelia Dekker displays a vial of the diluted smallpox vaccine that will undergo clinical trials at Stanford Hospital. The new study has the potential to shape U.S. policy regarding smallpox vaccination. PHOTO: SARA SELIS Researchers hypothesize that a diluted dose of the smallpox vaccine may be enough to protect previously vaccinated individuals — including most Americans over age 30. If this hypothesis were confirmed, the United States’ limited existing supply of the vaccine could be stretched further. The smallpox vaccine is no longer manufactured, but a supply is kept by the federal Centers for Disease Control and Prevention. "The key questions we’re studying are, does the smallpox vaccine we have from 30 years ago still produce a protective response in people who have already received the vaccine and can we dilute it to make a greater supply available to the U.S. population," said Cornelia Dekker, MD, associate professor of pediatrics at the School of Medicine and the medical director of the Stanford-Lucile Packard Children’s Hospital Vaccine Program. "The idea is that the more we can safely dilute this vaccine and still have it be effective, the more doses we can have available if we need them." In the Bay Area, Stanford has formed a partnership with Oakland-based Kaiser Permanente to conduct the randomized, double-blind study, which is funded by a grant from the National Institutes of Health. A total of 970 volunteers will participate in the study at nine sites across the nation. To test whether diluted doses can produce an effective immune response in previously vaccinated individuals, approximately 90 healthy volunteers between the ages of 32 and 70 will be enrolled at Stanford. Participants must have received the smallpox vaccine in the past, but not since 1992. Volunteers will be randomly assigned to one of three groups. One group will receive a full-strength dose of the vaccine. A second group will receive a dose that has been diluted five times, and a third group will receive a dose that has been diluted 10 times. All participants will be carefully monitored immediately following vaccination and will return to the medical center for at least eight clinic visits over the next two months. At these visits, participants will have their bandages changed, their vaccine site evaluated and may have blood drawn to monitor how the immune system reacts to the vaccine. Participants will be asked to record any side effects they may experience. Volunteers will be compensated for their time. In addition to determining the effectiveness of diluted doses, the study will give scientists other valuable information. It will help monitor the safety of the smallpox vaccine. It will help scientists understand how long the immunity from a previous vaccination lasts. And, significantly, it may help advance efforts now under way to develop a better smallpox vaccine with fewer side effects. "The way we understand immunity today is much more advanced than it was in the 1970s," Dekker said. "There’s a lot we can learn that could be very useful to those who are working on new vaccines." The study staff began screening potential participants this week. Those interested in volunteering should call 498-7423.
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Hospitals prepare for bioterrorism scare (6/26/02) Bioterrorism fears tackled in special grand rounds at Fairchild (10/24/02) |
Stanford Report, October 23, 2002
