Vaccines are made of treated viruses or bacteria. Vaccines do not cause disease. However, they are strong enough to start the creation of antibodies. Many vaccines contain certain bacteria or viruses that were killed or made weaker so that they could not harm people. Some use live organisms similar to agents that cause sickness. Another group of vaccines contains live pathogens. These pathogens are weakened, so they will not cause illnesses. Toxoids are another type of vaccine. These are made of poisons produced by disease-causing organisms. The poisons are chemically treated to be used in vaccines. They help give immunity without causing harmful effects.