Wars are usually launched with the promise of a quick victory, with trumpets primed never to sound retreat. And the campaign against AIDS was no exception. Soon after researchers announced in the mid-1980s that they had discovered the virus that causes AIDS, U.S. health officials confidently crowed that a vaccine would be ready in two years. The most frightening scourge of the late 20th century would succumb to a swift counterattack of human ingenuity and high technology.
But no one was making any victory speeches last week in Amsterdam, where more than 11,000 scientists and other experts gathered for the Eighth...