Many different types of vaccines are available, and these can be enormously successful in preventing some of the major communicable diseases particularly those that affect children if they are used correctly. We will teach you about the concepts and procedures required to deliver an effective immunization service in your community. In this first study session, you will learn about how the immune system protects us from infection, the general principles underlying immunization, the types of immunity and the types of vaccines available.

We will also explain the main features of the Expanded Programme on Immunization (EPI), and what you as a health professional can do to help to make it successful. Immunization benefits the whole country because it has the following general outcomes:

• It prevents millions of people dying needlessly each year.
• It has led to some diseases being eradicated from the world altogether, for example smallpox, and others are targets for elimination, e.g. polio and neonatal tetanus.
• It promotes health and optimal growth and development in children.
• It releases resources for other health interventions.
• It is an investment for a healthy population and a stronger economy.