The International Aids Conference is back in the United States for the first time in more than 20 years, with a star-studded cast that includes top U.S. health officials, former presidents, philanthropists, and public health officials from around the world. Recent years have seen major strides in the prevention and treatment of AIDS around the world, but challenges remain, including declining financial support, according to a recent UNAIDS report.

What do you see as the key successes of the global fight against AIDS? What future challenges most concern you?