Researchers at University Hospitals in Cleveland are set to test a new smallpox vaccine in a study to measure side effects and immune response in people with AIDS. If results are favorable, millions of immune-compromised individuals could be vaccinated against smallpox. The current vaccine, Dryvax, is not recommended for people with weak immune systems -- including diabetics, transplant recipients, elderly persons, small children, and HIV-positive people -- because they are more susceptible to its dangerous side effects.

Five other US hospitals are also participating in the study, which will enroll about 88 people, said Dr. Hernan Valdez, assistant professor of medicine at Case Western Reserve University and part of the AIDS Clinical Trials Unit at University Hospitals. The Food and Drug Administration must approve the protocol before the study can begin, which could take up to 30 days, said Dr. Lawrence Fox, medical officer for the HIV Research Branch of the National Institute for Allergy and Infectious Diseases. NIAID is sponsoring the study.

The study will test the safety and effectiveness of the modified Ankara vaccine (MVA). MVA has never undergone widespread testing in the United States, but Valdez said it produced only minor side effects in a recent German study of HIV-positive individuals. Soreness at the vaccination site was the primary side effect. In contrast, Dryvax, which is made from cow guts, can cause severe skin problems, blindness and brain inflammation. For every 1 million people vaccinated, 15 develop life-threatening problems and at least one dies. But while MVA is considered safer than Dryvax, scientists are not sure MVA alone can prevent smallpox. Dryvax, which is credited with eradicating smallpox throughout the world, is the only smallpox vaccine available in the United States.

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