A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe, its toxins or one of its surface proteins. The agent stimulates the body's immune system to recognize the agent as foreign, destroy it, and "remember" it, so that the immune system can more easily recognize and destroy any of these microorganisms that it later encounters.

The Integrated Service Delivery (ISD) and Primary Health Care (PHC) unit provides oversight of the WHO Regional Office for Africa’s work on the adoption of integrated people-centred health services, in line with the primary health care approach, for attaining universal health coverage (UHC), the health-related Sustainable Development Goals (SDGs) and other country-level health targets.