In this week's New England Journal of Medicine  Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, discusses prospects for an AIDS vaccine. He says while the ultimate goal is prevention, much like that for polio, smallpox and measles, combating the AIDS virus requires a non-traditional strategy in which a vaccine may not totally block infection, but could lower the level of virus and slow down transmission.

Fauci says one promising vaccine, led by the Merck pharmaceutical, uses a relatively benign common virus called an adenovirus. "You insert in that the different components of HIV and you vaccinate individuals with that particular vectored virus."

The National Institutes of Health is leading a similar research effort with large numbers of volunteers worldwide to test for safety and protective response.

Fauci says these interim vaccines would work in tandem with the two-dozen or so antiviral therapies currently available. "If you block the progression, but the person still has a significant degree of virus replication going on, you may need to have drugs come and supplement or complement the disease modifying vaccine."

Anthony Fauci says the success of the disease-modifying vaccines could be a major advance in the development of an AIDS vaccine. An estimated 14,000 new AIDS cases occur every day.