Mercy Ahun has more than 15 years experience working with immunization programs and is well acquainted with developing country health systems. She has worked at all levels of health delivery and brings experience in establishing systems for planning, implementing, monitoring and evaluating programs within the wider health system. Dr. Ahun joined the GAVI Alliance Secretariat in May 2003. She was formerly in charge of the Expanded Program on Immunization in her native country, Ghana.