How Vaccines Work

By: Alia Hoyt  | 

Edward Jenner
This illustration shows Edward Jenner vaccinating his young child, held by Mrs. Jenner. Wellcome Library, London/Wikimedia/CC BY SA-3.0

Medicine has come a long way over the years. The development of the vaccine kicked off an era of illness prevention unlike anything the world had ever seen. In fact, vaccinations are largely viewed as the most successful medical advancement in the history of public health. Before vaccines were introduced, smallpox killed millions, nearly 20,000 were paralyzed by polio, and rubella (German measles) caused serious birth defects in about 20,000 newborns.

In this article, we'll learn about the inspiration for vaccines, the basic science behind how they prevent illness and the diseases they keep at bay. We'll also go head-to-head with some of the common myths circulated about vaccines.


The Inspiration for Vaccines

Who knew that cows would save the lives of countless humans? In 1796, a physician named Edward Jenner decided to prove a theory that had been circulating for some time. Smallpox once killed millions of people worldwide. Cowpox was a less serious disease related to smallpox that milkmaids often caught through exposure to infected cows. Jenner noticed that milkmaids who had contracted cowpox were later immune to smallpox.

Jenner tested this theory when he took some infected cowpox matter and exposed an otherwise healthy boy through a cut in his arm. After the boy caught and recovered from cowpox, Jenner exposed him to smallpox via an injection. The boy remained healthy, and the world's first vaccine was born. The cows, for their part, were honored when the term "vaccine" was coined – "vacca" is Latin for cow. According to the national Centers for Disease Control and Prevention (CDC) the world's last case of naturally occurring smallpox was in 1977. The disease has since been eliminated from natural occurrences in the world, so the vaccine is no longer given.

Routine vaccines in the U.S. include:

  • Diphtheria
  • Hepatitis A
  • Hepatitis B
  • Hemophilus influenzae type b (Hib)
  • Human Papillomavirus (HPV)
  • Influenza
  • Measles
  • Meningococcal
  • Mumps
  • Pertussis (Whooping Cough)
  • Pneumococcal
  • Polio
  • Rotavirus
  • Rubella (German measles)
  • Shingles (Herpes Zoster)
  • Tetanus (Lockjaw)
  • Varicella (Chickenpox)

Non-routine vaccines in the U.S. which are given to people traveling to specific countries include:

  • Adenovirus
  • Anthrax
  • Cholera
  • Japanese encephalitis (JE)
  • Rabies
  • Smallpox
  • Tuberculosis
  • Typhoid
  • Yellow Fever

Source: CDC