HIV In San Francisco
A success story no one wants to hear:
While there was a ten percent decrease in total estimated new [HIV] cases, this seemingly modest decrease is actually a much greater prevention success than it appears. From 2001 to 2006, the estimated number of gay men living in San Francisco increased from 46,800 to 58,343. The increase was likely due to real growth in the gay community and, potentially, in part the result of an underestimation of the population size in 2001.
When the effect of the increase in the population size of [men having sex with men] is taken into account, new infections have decreased by an estimated 33 percent.
Sero-sorting - condom-free sex between people of the same HIV status - is a big reason why.