2. Start a discussion about the immune system and how the body has a natural defense system. Ask the students what there is to defend against. Discuss other types of immunity, for instance, a virus' ability to become immune to treatements and the body's ability to become immune to medication.
3. Discuss how vaccinations "trick" the body into producing antibodies to different diseases. Discuss how with the popularity of these vaccines different diseases have become "extinct". Discuss the reappearances of diseases and how they may have changed in order to surpass the current vaccinations.