We vaccinate against smallpox to allow the body to develop antibodies which will make it more or less immune to attack from the disease. In fact, by vaccination or inoculation we mean that a person is injected with the organism that causes the disease or its toxin (poison). This organism is modified physically or chemically, so that, without doing any damage, it triggers the body's immunizing defenses. We call these modified cultures vaccines.
Vaccination against smallpox was first carried out in the East. Poisonous material taken from the blisters of a mild case of smallpox was inserted into the arm of the person to be protected. This produced a mild case of smallpox and enabled the body to manufacture the antibodies.
Vaccination was introduced into England in 1721 by Lady Mary Wortley Montagu, wife of the British ambassador to Turkey, who had her own children inoculated at Constantinople. However, this method could result in a severe or fatal attack of the disease.
Dr. Edward Jenner took the next step in 1796 when he inoculated a boy named James Phipps with poisonous matter from the arm of Sarah Nelmes, a dairymaid suffering from cowpox (a mild disease closely allied to smallpox). Some weeks later he inoculated James Phipps with smallpox, but the boy did not contract the disease.
In 1798 Jenner published a book on his experiments and the practice of vaccination spread throughout the world. The principle has been applied to many diseases. Babies and young children are particularly susceptible to complications from whooping cough and diphtheria, so they are immunized soon after birth. Poliomyelitis (infantile paralysis), cholera, yellow fever, and typhoid are all dangerous diseases which inoculation has been able to control.