More than 900 years ago, Bedouins in the Negev Desert learned to prevent the onset of rabies by killing a rabid dog, roasting its liver and feeding it to a dog-bitten person, setting the stage for the world’s first oral vaccination.

Protection from smallpox took center stage in China, where white cow fleas collected from sick cows were used to prevent the disease. The fleas were ground into powder and made into pills.

Edward Jenner was one of many seeking to defeat the “speckled monster” of smallpox, and it was common lore that dairymaids seemed immune to smallpox after contracting cowpox. In May 1796, using matter from fresh cowpox lesions, Jenner inoculated an 8-year-old boy. In July, he demonstrated that the boy was protected from smallpox and called this new procedure vaccination, after vaccinia, the Latin name for cowpox.Jenner’s first paper on the subject, which described the first successful control of an infectious disease by the deliberate use of vaccination, was rejected.

The first laboratory vaccine was developed by Louis Pasteur for chicken cholera, an innovation now considered to be the birth of immunology. The concept of employing attenuated (or weakened) bacteria was actually a serendipitous discovery, after Pasteur’s lab assistant forgot to inject their chickens with fresh bacteria and instead used bacteria from a month earlier. Chickens inoculated with the old cultures became protected against the most virulent strains of bacteria. In his paper announcing these findings, Pasteur also used the term vaccination, in honor of the discoveries by Jenner that had inspired his own work.

Nine-year-old Joseph Meister had been mauled by a rabid dog. His distraught mother brought the boy to see Louis Pasteur, who had recently announced to the French Academy of Sciences that he had successfully protected dogs from rabies by use of his attenuated rabies vaccine. Could he help her son? Pasteur had never successfully used his vaccine in a human, nor was he a medical doctor, but he felt certain the boy would die if he did nothing. So Pasteur made a bold decision and began a course of 13 injections, once daily. The vaccine was a success, and young Joseph survived.

Leveraging insights from the Bedouins, Nobel laureate Charles Richet demonstrated that raw meat could cure tuberculous dogs.

In the face of a devastating polio epidemic, Jonas Salk believed that a vaccine with a “killed” polio virus could safely immunize without the risk of infection. In 1955, it was announced that Salk’s poliovirus vaccine was 80-90% effective against paralytic polio. Upon adoption of the vaccine, the average number of polio cases in the U.S. dropped from more than 45,000 to just 910. It is unlikely, however, that Salk was surprised by this success. His confidence in the protective powers of his vaccine was so high that, two years earlier, he had administered the vaccine to himself, his wife and their three sons.

On August 20, 1994, the Pan American Health Organization (PAHO) reported three years had passed since the last case of wild polio in the Americas. A 5-year-old Peruvian boy was the last registered case in 1991. Wild poliovirus was declared eliminated from the Western Hemisphere in September 1994, making the Americas the first World Health Organization (WHO) region to meet the goal of polio elimination.

Vaccines continue to be a topic of great interest to both citizens and healthcare professionals. Vaccination has substantially reduced the morbidity and mortality caused by infectious diseases, and yearly influenza vaccinations have become commonplace. Preventable diseases remain a significant issue, however, in many areas of the world where infrastructures for vaccination are poor and vaccines cannot be delivered where they are most needed. The future of immunization now looks to vaccines that are simple to administer, survive transport without refrigeration, and provide a long-lasting immune response.