Abstinence is the best cure for AIDs. Unfortunatly, we live in a world where people are encouraged to do whatever feels good to them, and to heck with the consequences.
One of the many legacies from the leftist counter-culture movement that is still being encouraged by former hippies in high places.
Failure to change behavior is the ONLY thing holding back progress in the fight against AIDS.
An aids vaccine certainly has some utility, particularly for health care workers and others at possible risk for infection.
But for homosexuals and drug addicts, it was always a pointless exercise. Even if aids were conquered, there will always be new and different infections and health crisis attached to these unhealthful behaviors popping up.
Long before aids was discovered, an old doctor friend of mine told me young homosexual men would suddenly get mysteriously and deathly ill at a much higher rate than the general population.
Conquering aids would do nothing for the long term health of gays.
The big problem, with AIDS, is the initial infection with HIV leads to an auto-immune destruction of the T-helper cells. A vaccine might also initiate the auto-immune response, especially if it is keyed to the particular protein sequence, in the HIV virus, associated with the initiation of the auto immune response.
It may possible to develop a vaccine that will key to a different protein sequence of the HIV virus. If that can be done, the vaccine would a lower probability of initiating the auto-immune response that leads to AIDS.
Still, avoiding sexual promiscuity is the best preventive measure.