Prevention: changing focus in San Francisco.
D017280:Condoms / Q000706:statistics & numerical data; D015658:HIV Infections / Q000453:epidemiology / Q000517:prevention & control*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D018671:Needle-Exchange Programs; D012495:San Francisco / Q000453:epidemiology; D015819:Substance Abuse, Intravenous