The investigational vaccines, manufactured by Massachusetts-based Acambis Inc., will be compared with the existing smallpox vaccine, known as Dryvax. The new vaccines were produced using modern methods of cell cultivation. Dryvax, the same smallpox vaccine that was provided to all U.S. residents during the period of routine smallpox vaccination, hasn't been produced in many years.
"Although there has not been a case of smallpox in the United States since 1949, the U.S. government has determined that it is necessary to keep smallpox vaccine available, in case the disease is reintroduced through bioterrorism," said Sharon Frey, M.D., principal investigator for the study and associate professor of internal medicine in the division of infectious diseases at Saint Louis University School of Medicine. "A study starting this fall at Saint Louis University is being done to determine the effectiveness of two new investigational smallpox vaccines in healthy adults."
The study will include 90 adult volunteers: 30 receive one newly produced smallpox vaccine, 30 receive the other new vaccine and 30 will receive Dryvax. Like the two newly manufactured vaccines, Dryvax is also considered investigational because researchers will use a different "diluent" to change the vaccine from its dry state (how it's stored) to its liquid state (how it's administered).
"The effectiveness of these smallpox vaccines will be measured by observing whether or not a 'pock,' which resembles a blister, forms at the site of the vaccination, and through blood tests," Frey said. The pock is a typical response to smallpox vaccination and leaves a small scar or depression on the skin at the site of vaccination.
Contact: Joe Muehlenkamp
Saint Louis University