Vaccinating

Vaccination is the administration of a vaccine to help the immune system develop protection from a disease. Vaccines contain a microorganism or virus in a weakened, live or killed state, or proteins or toxins from the organism. In stimulating the body's adaptive immunity, they help prevent sickness from an infectious disease. When a sufficiently large percentage of a population has been vaccinated, this results in herd immunity. The effectiveness of vaccination has been widely studied and verified.

History

The concept of vaccination was pioneered by Edward Jenner who discovered in 1796 that milkmaids who had previously caught cowpox did not later catch smallpox. Building on this observation, Jenner discovered that inoculating a person with cowpox could protect them from smallpox. With the discovery of the germ theory of disease, vaccines became a key tool in preventive medicine.

Types of Vaccines

There are several types of vaccines. Each type is designed to teach your immune system how to fight off certain kinds of germs — and the serious diseases they cause.

• Live-attenuated vaccines fight viruses and bacteria. These vaccines contain a version of the living virus or bacteria that has been weakened so that it does not cause serious disease in people with healthy immune systems.
• Inactivated vaccines also fight viruses and bacteria. These vaccines are made from the virus or bacteria that has been killed or parts of the virus or bacteria.
• Subunit, recombinant, polysaccharide, and conjugate vaccines use specific pieces of the virus or bacteria — like its protein, sugar, or capsid (a casing around the virus).
• Toxoid vaccines prevent diseases caused by bacteria that produce toxins (poisons) in the body. In the process of making these vaccines, the toxins are weakened so they cannot cause illness.

Vaccination Schedule

The World Health Organization (WHO) and the Centers for Disease Control and Prevention (CDC) provide vaccination schedules that are designed to protect individuals and populations from the diseases that vaccines can prevent.

Side Effects

Vaccines are very safe, and side effects are rare. The most common side effects are mild, such as a sore arm or mild fever. Serious side effects are extremely rare.

See Also

• Immunization
• Vaccine hesitancy
• Vaccine-preventable diseases
• Vaccine development

Vaccinating Resources
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