The disease progressions can result in different immune response in the host. The interactions between diseases and immune responses bring about various pathological changes or effective disease-resistance mechanisms in the host. This course will introduce the immune mechanisms caused by HIV, Malaria, Trypanosomes, Enterovirus, Severe Acute Respiratory Syndrome (SARS) virus, COVID-19 virus, Dengue virus, hepatitis virus, allergic reaction, and so on. The effects of these immune mechanisms on host health are also discussed in this course.