The vaccine is an invention that produces immunity against a disease. Vaccines can prevent diseases at their root cause. The vaccine works with the host immune system to prevent viral infection. it can break the chain of transmission. Vaccines provide active and passive immunity. Vaccines are equipped with the entire disease-causing microorganisms or some of their components. The smallpox vaccine is the first successful vaccine. Immunotherapy is the action that uses certain parts of a person’s immune system to fight diseases such as cancer.