Vaccines are one of medicine’s greatest achievements. Without vaccinations, millions of children and adults would contract serious diseases that are now prevented by vaccines, and many would have long-lasting effects or even die. In fact, vaccinations are one of the most important public health measures for preventing disease.
Smallpox was a highly contagious, rapidly spreading disease. It affected people of all ages and races, leaving scars on the face and body and often causing death.
During the 15th century, an early form of smallpox vaccination was practiced in China and other parts of the world. Healthy people were intentionally infected with substances from the pustules of people suffering from smallpox, a technique called variolation. A mild form of smallpox usually resulted from this practice.
Later, in the 18th century, this practice was adopted in England, where smallpox was the most common disease, causing 20% of all deaths in London. An expression of the times was, “Mothers counted their children only after they had had the smallpox.” An English doctor, Edward Jenner, replaced the variolation technique to create the first vaccine in 1796. Dr. Jenner had heard that dairymaids who had been infected with cowpox, a disease related to but milder than smallpox, were not susceptible to smallpox, and decided to test the idea. He performed the first vaccination on a boy with material taken from lesions of cowpox. In fact, the word vaccination comes from the Latin word for cow, vacca. People who received the vaccine were immune to smallpox.
In the 19th century, vaccination laws were established in Europe and the United States, and people began to be vaccinated against smallpox routinely. In the 20th century, vaccination against smallpox became a worldwide effort.
The last case of smallpox in the United States was reported in 1949, and routine vaccination of children in the United States ended in 1971. The last case of smallpox in the world was in Ethiopia in 1976. In 1980, scientists announced that vaccines had been successful at eradicating smallpox from the world.
In addition to smallpox, several other deadly diseases have been controlled as a result of vaccines. In fact, vaccination has resulted in the elimination of polio from the Western Hemisphere. Since the introduction of vaccines, diseases that once caused thousands of childhood deaths in the United States each year are now so rare that few parents have seen them. For example, diphtheria declined from a high of 206,939 cases in 1921 to just one in 1998; whooping cough declined from 265,269 cases in 1934 to 6,279 in 1998; and measles has fallen from 894,134 cases in 1941 to just 89 in 1998.
The ultimate goal of immunization programs is to prevent or eliminate infectious disease. For infectious diseases that can only be transmitted from person to person, immunization results in the elimination of the disease and, eventually, can achieve the eradication of the organism that causes it. This was the case with smallpox, and may be the case with two other diseases: polio and measles.
Poliomyelitis has been eliminated from the Americas, but because people who are not vaccinated and may become infected when they travel can carry the polio virus from other parts of the world to the United States, vaccination is still necessary. However, it is expected that polio will be eradicated sometime early this century.
Measles has also been markedly reduced in the United States as a result of effective vaccination of children. But measles is one of the most highly contagious diseases. In other parts of the world, measles accounts for one million deaths every year. Even in the United States, measles outbreaks have occurred in areas where vaccination rates fell. In 1998, 71% of measles cases in the United States were imported from outside our borders.