The typical vaccine introduces the foreign body to our immune system, enabling it to build up protection to fight off real infection. The DNA vaccine, however, uses just a few genes of a virus. Tests in animals reveal that the genes slip into cells, which then appear to be infected. The immune system often responds more vigorously than it would to a typical vaccine. For example, a DNA vaccine could offer longer-lasting protection than a flu shot that must be administered yearly.
Some doctors greet the new treatment warily.
For that reason, there is a great deal of safety concern and caution. Thus far, no safety problems have been identified in volunteers such as Carroll. Welcome to the CDC National AIDS Clearinghouse AIDS Information Newsletter Feedback Send us your comments. Selected responses are posted daily. External sites are not endorsed by CNN Interactive.