Researchers at six U.S. hospitals are planning to test a new smallpox vaccine in people with AIDS to determine if the vaccine is safe to give to people with compromised immune systems. Earlier reports have suggested that a nationwide smallpox vaccination plan to thwart a possible bioterrorism attack would likely have to skip people with AIDS, those taking antirejection drugs following transplant surgery, and others because people with compromised immune systems are prone to serious side effects of the vaccine and possibly may even develop smallpox. Life-threatening side effects from the vaccine, called Dryvax, occur in about 15 of every 1 million people in the general population who are vaccinated, and one of every million dies of vaccine-related complications.
The study, which will enroll about 90 people, will test the effectiveness of a modified vaccine that developers say is safer than Dryvax. The Food and Drug Administration is currently reviewing the study protocol and is expected to approve the clinical trial before the end of the year. The study will likely begin next spring.