1. Coverage & Equity Unit, Immunization Section, PG-Health, UNICEF Headquarters, 3 UN Plaza, New York, NY 10017, USA
2. College of Public Health, University of South Florida, Tampa, FL 33612, USA
3. Nuffield Department of Women’s and Reproductive Health, University of Oxford, 75 George Street, Oxford OX1 2JD, UK
4. Johns Hopkins Bloomberg School of Public Health, International Vaccine Access Center (IVAC), Baltimore, MD 21231, USA
5. New Vaccines and Immunization Systems, Bill and Melinda Gates Foundation, New Delhi 110067, India
6. John Snow, Inc., 2733 Crystal Drive, Arlington, VA 22202, USA
7. Department of Immunization Vaccines and Biologicals, WHO Headquarters, Avenue Appia 20, 1211 Geneva, Switzerland