Vaccine immunology is the science of disease prevention through the use of vaccines. Vaccines are weakened forms of the microorganisms that cause various dangerous diseases. When introduced into a patient’s system, a vaccine activates the body’s natural immune system. As a result, the patient will be immune to the disease in later life. While it is not without controversy, vaccine immunology has saved millions of lives worldwide since its introduction in the 18th century.
The discovery of vaccine immunology is credited to the British physician Edward Jenner. Jenner investigated claims that people were immune to the deadly disease smallpox if they had been exposed to cowpox, a similar but non-fatal disease. In 1796, Jenner tested this theory by inoculating, or injecting, a young patient with cowpox, then later with smallpox. Although the patient contracted and recovered from cowpox, he proved immune to smallpox. The successful creation of the smallpox vaccine led to the worldwide eradication of the disease by the 1980s.
All higher organisms have natural immune systems consisting of microscopic structures called antibodies that battle disease and other infections. When faced with a specific disease, the body can manufacture specialized antibodies; this is why, for example, a person infected with chickenpox once will normally be immune to the disease in the future. By introducing a weakened form of a dangerous disease, vaccine immunology causes the creation of specialized antibodies that will protect the patient in case of future exposures. Some patients do contract the disease from the vaccine, but this incidence is far less than in populations that have not been vaccinated.
Not all diseases can be prevented by vaccine immunology. Some diseases, such as the common cold, influenza, and AIDS, are caused by microbes called viruses. Unlike bacteria, viruses do not have a set genetic structure, and can easily mutate into new forms. Even if a person has been vaccinated against one kind of flu, for example, other kinds of flu may not be affected; this is why effective vaccines for these diseases have long been elusive. Nevertheless, numerous fatal diseases of the past have been controlled or wiped out by vaccines, including polio, whooping cough and tuberculosis.
In the 1990s and early 2000s, there were concerns worldwide that childhood vaccinations were linked to autism, a developmental disorder. It was feared that small concentrations of mercury used as preservatives in vaccines could cause brain damage. The use of mercury preservatives was discontinued, but numerous scientific studies found that these fears were groundless. The doctor who claimed that Measles Mumps Rubella (MMR) vaccines were dangerous was later found to have manipulated data, and he was stripped of his medical license. Vaccine immunology remains an important life-saving measure for populations around the world.