When you have studied this session, you should be able to:

• Define and use correctly all of the key words printed in bold.
• Describe how the human immune system protects the body from infection, and distinguish between the main types of immunity.
• Describe the main general types of vaccines and what they contain.
• Describe the main features of the Expanded Programme on Immunization (EPI) and how health professionals can help to achieve its strategies.