Military veterans who want to make a patriotic contribution. Local government officials who might be needed in a biowarfare emergency. Citizens who were touched by the events of September 11, 2001.
Those are many of the 90 people who have signed up to be part of a clinical trial of smallpox vaccine at the Medical Center, says Cornelia Dekker, research associate professor of pediatrics and medical director of the Stanford-Lucile Packard Children’s Hospital vaccine program. The study, funded by the National Institutes of Health and involving more than 900 people at nine sites in the United States, is designed to test whether diluted doses of the smallpox vaccine will produce adequate immunity in previously vaccinated adults. Smaller NIH studies have shown that a dose of the vaccine diluted to a one-fifth concentration is effective for people who are being vaccinated for the first time.
Although the last case of smallpox in the United States was in 1949 and routine immunization ended in 1972, the federal Centers for Disease Control and Prevention kept a limited supply of the vaccine. That agency has assured the public that there is enough vaccine for everyone who would need it in the event of an emergency. The clinical trial Dekker is conducting with Kaiser Permanente will help policy-makers decide how to deal with an outbreak.
The study will compare the effectiveness of undiluted vaccine with one-fifth and one-tenth concentrations. Dekker and her colleagues also will draw blood from the subjects before and after vaccination to assess their antibody levels. “One of the questions people are asking is, ‘How long does protection last?’ ” she says. “I don’t know that we’ll come up with a definitive answer, but we will be looking at what the antibody level is before the [trial] vaccination and seeing how much we can goose that. We can at least say something about whether the body still has any virus-fighting ability left from the old vaccine.
“The tragedy for many of us in the field of vaccines is that this was our biggest success story,” Dekker says. “We developed a vaccine and wiped smallpox off the face of the earth, and now we have to bring back the vaccine, still absent natural smallpox in the world. It is a little depressing, but in these unusual times, it’s important for the government to be prepared.”
