Topical drug best for smallpox vaccine side effects

A variety of potentially serious infections can occur after immunization with the smallpox vaccine. Now, findings from an animal study suggest that a topical form of cidofovir, an anti-viral drug, is better than an intravenous form at treating such infections.

"The implications of our study are that severe, progressive infections that can occur following smallpox vaccination would be much better treated with topical cidofovir than with the intravenous drug," Dr. Donald F. Smee, who led the study, told AMN Health.

Smee and colleagues from the Institute for Antiviral Research at Utah State University in Logan exposed the wounded skin of mice to vaccinia virus, the virus used in the smallpox vaccine. The mice, which had defective immune systems and could not fight off the virus, were treated with topical (cream), intravenous, or both forms of cidofovir.

The new findings appear in The Journal of Infectious Diseases.

As expected, the animals developed overwhelming infections. Both forms of cidofovir were effective in delaying death, but the topical form was better than the intravenous form at reducing the number of infected body sites as well as virus levels in the skin.

Animals treated with both topical and intravenous cidofovir had the greatest reduction in infection severity and survived the longest.

"Presently, cidofovir is formulated for intravenous use," Smee told Reuters Health. "I believe that the FDA is still in the process of approving cidofovir for treatment" of smallpox vaccine complications, he added.

SOURCE: Journal of Infectious Diseases, September 15, 2004.