Vaccination
The principle behind inoculation or vaccination is relatively simple. A milder, weakened, or similar variant of an illness is introduced to the body to trigger a natural immune response. The immune response then provides the individual with long-term resistance to the illness. The first immunization significantly predated any real understanding of germ theory.
The first form of inoculation was variolation. Variolation or the controlled transfer of pus from a smallpox lesion to a healthy person’s arm was intended to produce a very mild version of the illness. The individual would become sick, but recover and have immunity. Variolation was first practiced in Asia in the 1600s.
In the 1790s, Edward Jenner recognized that milkmaids, who commonly contracted cowpox, were immune to or largely resistant to smallpox. Unlike smallpox, which was quite serious and could lead to death in many cases, cowpox was a relatively mild illness. Jenner took pus from a cowpox sore and inoculated a young boy with it, later exposing the child to smallpox on multiple occasions. The boy never developed smallpox. By 1800, 100,000 people had been vaccinated against smallpox in Europe.
No additional improvements were made in vaccination technology until Pasteur’s development of a rabies antitoxin in the middle of the 19th century. The polio vaccine brought an end to the polio epidemic of the 1950s. Additional vaccines were developed for many other previously common illnesses, including diphtheria, pertussis, measles, mumps, and rubella.
In the United States alone, each year, immunizations prevent some 33,000 deaths. The availability of vaccinations has dramatically reduced childhood mortality rates, thereby extending the overall life span.