Introduction

Vaccines are liquid solutions containing dead or weakened forms of infectious microbes that are injected into the body to produce immunity from disease. Vaccinations typically work by inducing the immune system to generate antibodies that attack certain viruses or bacteria. Because the microorganisms contained in vaccines are weak or inactive, their presence can strengthen the body's natural defenses without causing illness. Vaccines also enable the immune system to react quickly and effectively when threatened by disease in the future.

The concept of immunization through inoculation is considered to be one of the most significant advances in scientific history. Western medicine's introduction to the practice most likely occurred in the eighteenth century, when traveling British aristocrat Mary Montagu reported her observations of Turkish children being injected with pus from smallpox victims. Most of these children would contract a mild version of the illness yet later retain a lifelong...