May 2000 • Volume 6 • Number 5
Vaccinate against smallpox? Preposterous! But will a vaccine be there if you need it?
BY CINDY McCANSE
It's no secret that we live in dangerous times. Responding to mounting concerns about worldwide terrorist threats, U.S. officials are seeking ways to protect American citizens from biological terrorism.
Smallpox lesions cover the face of the young boy in this archival photo.To this end, the NIH is currently funding a phase II clinical trial to gauge the immunogenicity of diluted doses of existing smallpox vaccine. This spring, the Center for Vaccine Development at Saint Louis University School of Medicine, the sole study site, began seeking participants.
Variola major, the virus that causes smallpox, is considered a potential bioterrorism agent. The highly contagious disease was declared eradicated in May 1980, thanks to a global vaccination program spearheaded by the World Health Organization. Only two known stocks of the virus remain: one at the State Research Center of Virology and Biotechnology in Koltsovo, Russia, and the other at the CDC in Atlanta.
But some experts fear that hostile parties may also have caches of the virus.
Manufacturing of the smallpox vaccine, Dryvax, ceased in 1983. About 15.4 million doses of vaccine remain in the United States, many of which may be unusable. The CDC controls distribution of the vaccine, which is now given only to laboratory workers at risk of occupational exposure to smallpox and to at-risk U.S. military personnel.
"The reason for doing this study is to see if we can increase the available number of doses in the event of a bioterrorist attack or biowarfare," said lead investigator Sharon Frey, M.D., associate professor of infectious diseases and immunology at SLU. "Being able to successfully dilute the vaccine would potentially increase the available stock by 10- to 100-fold."
Of 60 participants to be recruited for the double-blinded, randomized study, one-third will receive the full dose of vaccine, one-third will receive a 10 percent dilution and the remaining one-third will receive a 1 percent dilution.
Meanwhile, the U.S. Army Medical Research Institute of Infectious Diseases and the Joint Vaccine Acquisition Program, both at Fort Detrick, Md., are working to develop a tissue culture-derived smallpox vaccine. Clinical trials have already begun, and it is possible that the vaccine could be licensed by 2003.
"They're working on developing newer forms of vaccine product," said Frey. "What we're doing is really an interim step, waiting for a better product to come along."
FP Report is published by the AAFP News Department.
Copyright © 2000 by American Academy of Family Physicians.
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