title: PEP must begin early.
mesh_terms: D044966:Anti-Retroviral Agents / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D015658:HIV Infections / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control*; D015277:Hotlines / Q000706:statistics & numerical data*; D006801:Humans; D012495:San Francisco / Q000453:epidemiology; D047568:Unsafe Sex / Q000706:statistics & numerical data
chemical_list: D044966:Anti-Retroviral Agents