1. Division of HIV/AIDS Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA
2. Division of STD Prevention, National Center for HIV/AIDS, Viral Hepatitis, STD, and TB Prevention, Centers for Disease Control and Prevention, Atlanta, GA, USA
3. Oak Ridge Institute for Science and Education, Centers for Disease Control and Prevention, Atlanta, GA, USA
4. RTI International, Research Triangle Park, NC, USA