1. Immunization Systems Branch, Global Immunization Division, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
2. FOCUS 1000, Freetown, Sierra Leone
3. Expanded Program on Immunization, Ministry of Health and Sanitation, Freetown, Sierra Leone
4. Epidemic Intelligence Service, U.S. Centers for Disease Control and Prevention, Atlanta, Georgia, USA
5. Health Education Division, Ministry of Health and Sanitation, Freetown, Sierra Leone
6. Sierra Leone Country Office of U.S. Centers for Disease Control and Prevention, Freetown, Sierra Leone
7. Yale Institute of Global Health, Yale University, New Haven, Connecticut, USA
8. Department of Health Behavior, Gillings School of Global Public Health, University of North Carolina, Chapel Hill, North Carolina, USA