But while dozens of potential vaccines are in development, only two AIDS vaccine candidates are in advanced human trials -- one made by Merck and Co. and another by Sanofi-Aventis SA.

• 虽然有十几种疫苗在研，但仅有两种侯选的艾滋病毒疫苗接受人体试验，一种由Merk(默克)公司制造，另一种由Sanofi-AventisSA制造。