PIP: Further attenuated measles vaccine has been given to 13 million children in 19 West and Central African countries as part of a regional program of smallpox eradication and measles control. Measles transmission has been significantly reduced in most countries and interrupted only in Gambia. Analysis of measles cases in the post-campaign period has identified measles in nonparticipants in the mass campaign, new susceptibles, and in a small number of vaccines. Although the original program envisioned recycling, the immunization of new susceptibles, every 2-3 years, epidemiological investigation has indicated that the frequency of recycling must be increased to achieve effective control. The current development of maintenance programs is directed at maximum utilization of mobile teams and static health facilities to achieve immunization of new susceptibles every 6 months in high density population areas and every 12-18 months in low density areas. (author's)