The mission of NESI is to improve the quality and sustainability of immunisation programmes and services, in particular in low- and middle-income countries, through education and training, technical support, operational research and networking and advocacy.

NESI aims to build the capacity of managers and staff working in the Expanded Programme on Immunisation (EPI) in their respective countries, as well as to improve pre-service and post-graduate training at the different faculties of health training institutions involved in immunisation, including medicine, nursing, pharmacy, and public health. NESI also aims to strengthen the capacity of the National Immunisation Technical Advisory Groups (NITAGs) in evidence-based recommendation-making.

To accomplish its mission, NESI engages in a number of activities, which are grouped into four strategic areas:

• Education and training
• Technical support
• Operational research
• Networking and advocacy