I just read about this vaccine. If this is true, couldn't it be used in HIV infected patients to boost their immune systems?

Merck To Double Enrollment in AIDS Vaccine Trial After Promising Results

"Researchers conducting clinical trials of an AIDS vaccine made by Merck will double enrollment in the trials to 3,000 participants after results exceeded their expectations. The trials are aimed at determining whether volunteers' immune responses can prevent or control HIV. The vaccine, called MRKAd5, contains an adenovirus -- a common cold virus -- that carries manmade copies of three HIV genes that are designed to stimulate the body's CD4+ T cells. Researchers have found that the vaccine has boosted participants' T cells 50 to 100 times their baseline number, a response comparable to the immune reaction to vaccines for diseases such as smallpox and measles. However, the vaccine does not prompt the body to generate antibodies, which are essential to immune protection."

I can't speak to the specifics of this vaccine. However, some vaccines are being developed as preventative (to prevent infection) and some are being developed as therapeutic (boosting the immune system of those already infected) vaccines.