Sabin polio vaccine is taken orally. A single dose of some vaccines provides lifelong protection against infection. Other vaccines require several doses to produce immunity and then must be reinforced at regular intervals with booster doses. Toxoids for diphtheria and tetanus are generally combined with whooping cough vaccine. Protection against measles, mumps, and rubella also may be provided in one vaccine.
Most vaccines begin to provide immunity about two weeks after they are administered.
Centers for Disease Control and Prevention, Advisory Committee on Immunization Practices. Other vaccines, such as those for cholera and yellow fever, are given only to persons who plan to travel to places where the disease is widespread. Vaccines for some rare diseases are given only to those who may be exposed to them. Vaccines are safe and dependable, but they are not perfect. For example, up to 10 percent of all the people who are vaccinated against a particular disease may not be protected.