“The first thing we have to remember is that behavior change works,” she said. “In the beginning of the HIV epidemic in the United States, seroincidence in gay men was as high as 20% per year. And now, even in the most heavily impacted subpopulations of men who have sex with men, we're talking about incidence rates of 2%–5% per year. So we've had a substantial decline in the rate of new infections, and that's all because of behavior change.”