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 contain 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.
Vaccines have been effective in controlling epidemics.Vaccines are also less expensive than treating the disease.As a result,several governments have adopted laws that call for all citizens to receive certain vaccinations.
For example, the government of Great Britain introduced a law in 1853 for nationwide vaccinations