History of Vaccines: Part 1
A vaccine tricks the body’s immune system into producing antibodies to fight a form of the virus that is not harmful. Then, if the person ever encounters the real and dangerous virus, the body is ready to prevent it from harming any cells.
An Idea in Search of a Method
If everyone in a room suddenly became exposed to the same disease in the same way at the same time, everyone would not be equally affected. One of the most important factors in determining how or whether a person gets sick is immunity—the human body’s own ability to prevent disease.
It has been recognized for centuries that some diseases never reinfect a person after recovery. Smallpox was the first disease people tried to prevent by intentionally inoculating themselves with infected matter. Inoculation originated in India or China some time before 200 BC.
The concept of immunization, or how to artificially induce the body to resist infection, received a big boost in 1796, when physician Edward Jenner inoculated a young boy in England and successfully prevented him from getting smallpox. Jenner used a lancet to scratch some infected material from a woman with cowpox (similar to smallpox) under the boy’s skin.
Can’t Catch This: Immunity and Immunization
Lack of immunity to disease has helped to decide the fate of entire communities, from smallpox among the Indians in the New World to syphilitic soldiers in the Old. Most people have some amount of natural immunity. The human body can take care of itself in many circumstances—cuts, colds, and minor infections disappear without major upheaval. In other cases, the body has little or no naturally occurring immunity. So if you are exposed to diseases such as polio, influenza, smallpox, hepatitis, diphtheria, measles, or whooping cough, you will probably get sick with it unless you have been immunized.
Immunization refers to the artificial creation of immunity by deliberately infecting someone so that the body learns to protect itself. An important part of the history of immunization has been determining how to get the immunizing agent into the body. The skin, which keeps germs and injurious substances out, is also a barrier to getting medicines and vaccines into the tissue where they can work. Physicians have used varying methods to create immunity where there was none.
The Skin Factor
While some scientists and physicians studied how the body worked and how to persuade it to fend off diseases, others puzzled over how to insert medicines and other substances such as vaccines. Having an effective vaccine that could produce sufficient immunity was useless without being able to get it into the body in a harmless way. Edward Jenner used a lancet and scratched two lines on James Phipps’s arm. Fifty years after Jenner, the hypodermic syringe became available. In 1885, scientist Louis Pasteur used one to vaccinate a young boy who had been bitten by a mad dog and was sure to die of rabies—the boy lived, and immunization took another giant step forward.
As more immunizing agents became available, people saw the benefit of immunizing large groups, such as soldiers. During World War I, they were vaccinated against typhoid and smallpox; during World War II, typhus and tetanus.
The Future Has a Past
In the 19th century, use of the hypodermic syringe was limited by dependence on large needles that could rust or snap in two, glass barrels that cracked, and tips that leaked. Before disposable needles in the 1960s, needles needed to be sharpened and sterilized. Since then, technological improvements include sharper, thinner needles and safety features. Still, more than a few people would like to avoid a shot in the arm.
Hypodermic injection remains the most common method of getting through the skin, but it is not the only technology for immunization. Engineers and scientists continue to search for alternative routes into the body, such as through the mouth or nose. Continuing to solve the technological problems is critical for countries in which illness and death rates are high as a result of measles, maternal tetanus, and other preventable diseases.
A successful instrument or system must get the vaccine into the body with minimal disruption and be cost-effective for use with billions of people. Perhaps the most important problem today—preventing reuse of syringes to avoid cross-contamination—was not even imagined in the 19th century.