1 Polio Eradication Programme, World Health Organization Regional Office for Africa, Djoue PO Box 06, Congo (Brazzaville); Vaccine-Preventable Diseases Programme, World Health Organization Regional Office for Africa, Djoue PO Box 06, Congo (Brazzaville). Electronic address: [email protected].
2 World Health Organization Country Office, Juba, South Sudan.
3 Vaccine-Preventable Diseases Programme, World Health Organization Regional Office for Africa, Djoue PO Box 06, Congo (Brazzaville).