11 Pioneers in Vaccine Development You Should Learn About

From early inoculation practices to cutting-edge DNA and mRNA technology, vaccines for the world's deadliest diseases have progressed immensely over the centuries. Today, thanks to these monumental advancements in public health, countless lives have been spared globally. Here are 11 vaccine innovators who made a difference.

1. Onesimus // Smallpox

Onesimus, an enslaved African man, brought the practice of variolation (an early method of immunization against the smallpox virus) to the Puritans in colonial Boston. In the early 1700s, while in West Africa, Onesimus had undergone a unique medical procedure: He had pus from an infected individual rubbed into an open wound on his arm to build immunity. This technique was used in Africa, Turkey, and China to protect individuals from serious diseases. When Onesimus shared this knowledge with his enslaver, Cotton Mather, it led to the promotion of variolation during the smallpox epidemic in 1721 [PDF], helping to save numerous lives in Boston.

2. Edward Jenner // Smallpox

In the 18th century, many European physicians practiced variolation to protect against smallpox. Edward Jenner, a perceptive English doctor, observed that dairy workers infected with cowpox (a virus that was not harmful to humans) seemed immune to smallpox (a deadly virus for humans). In May 1796, Jenner took material from a cowpox lesion on Sarah Nelms, a milkmaid, and injected it into 8-year-old James Phipps. The boy felt ill for a few days, then recovered. Two months later, Jenner exposed Phipps to smallpox pus—and the boy remained healthy, proving a safer method to gain immunity against the more dangerous disease. Jenner coined the term vaccination, from the Latin word vacca, meaning “cow” (to distinguish it from variolation, the smallpox procedure).

3. Louis Pasteur // Rabies

Louis Pasteur, famous for developing pasteurization (heating food to eliminate pathogens), was also pivotal in creating a rabies vaccine. In the 1880s, with rabies spreading among the stray dogs in Paris, veterinarians sent Pasteur tissue samples from infected dogs. Pasteur injected the infectious material into rabbits’ brains to observe the viral effects. Through experimentation, he found that drying the infected tissue weakened the virus. He then created a vaccine by attenuating the virus in rabbits, making it less potent. This vaccine successfully prevented rabies in both dogs and humans.

4. Max Theiler // Yellow Fever

Theiler found that the yellow fever virus (which causes a severe tropical disease characterized by liver failure and gastrointestinal bleeding) could be transmitted to mice. This discovery made his research to develop a yellow fever vaccine more affordable and efficient, as he had previously relied on expensive monkeys for his experiments. Theiler ultimately created two types of yellow fever vaccines. One was a weakened strain, used in the 1930s and 1940s to protect people in West Africa. The second version was cultured in chicken embryos, making it more effective and easier to produce, leading to widespread use by 1937. In 1951, Theiler was awarded the Nobel Prize in Medicine for this groundbreaking achievement.

5. Thomas Francis // Influenza

Thomas Francis, an American microbiologist, made significant contributions to our understanding of the influenza virus and its prevention. By studying respiratory samples and serum from infected children, he was able to observe the virus’s impact on the human respiratory system. His team developed a vaccine effective against both influenza A and B, first successfully used during World War II in the early 1940s.

6. Jonas Salk // Polio

Jonas Salk’s development of a vaccine against poliovirus (a virus that can lead to paralysis and other neurological issues) made him a national hero. Unlike many of his contemporaries, Salk believed that a “killed-virus” vaccine could be just as effective, and possibly safer, than a “live-virus” version. He created a method to deactivate the virus with formaldehyde, rendering it incapable of reproducing. Salk’s vaccine tricked the immune system into producing antibodies to fight the virus. Confident in his innovation, Salk tested it on his own family before it was approved in 1955.

7. Albert Sabin // Polio

Salk’s rival, Albert Sabin, developed an oral polio vaccine in the 1960s. This was a “live” vaccine made by attenuating the poliovirus (which first affects the gastrointestinal system before targeting the nervous system). Sabin’s oral vaccine was not only easier to distribute and administer but also more affordable to produce, leading to its replacement of Salk’s injected vaccine by the early 1960s. Since polio outbreaks often occurred during the summer months, when contaminated bodies of water spread the virus, Sabin became affectionately known as “the doctor who gave summer back to children.”

8. Maurice Hilleman // Measles and More

Maurice Hilleman, an esteemed American microbiologist with a focus on vaccinology, developed over 40 vaccines during his extensive career at Merck. His contributions include vaccines for MMR (measles, mumps, rubella), Hepatitis A, Hepatitis B, chickenpox, and several others. Many of these vaccines have become standard in pediatric care, recommended as part of routine vaccinations for children.

9. Richard Mulligan & Paul Berg // Recombinant DNA Technology

Richard Mulligan and Paul Berg, biochemists from Stanford, were trailblazers in recombinant DNA technology, a groundbreaking method of creating vaccines by combining DNA fragments to generate a new “recombinant” molecule with specific functions. Their research involved transferring genes from bacteria, like E. coli, into monkey cells, allowing mammalian cells to produce bacterial proteins. This recombinant DNA technique led to the development of the hepatitis B vaccine in 1986, the HPV vaccine in 2006, and the flu vaccine in 2013.

10. Katalin Karikó // mRNA Technology

Katalin Karikó, a brilliant Hungarian scientist, dedicated her career to researching messenger RNA, the molecular messenger that helps translate genetic instructions into proteins. Despite early doubts from the scientific community, Karikó firmly believed that mRNA could revolutionize vaccine technology. She collaborated with Drew Weissman, a researcher from the University of Pennsylvania, to unlock the potential of mRNA vaccines. These vaccines work by instructing cells to produce a protein (or part of a protein) that triggers an immune response and generates antibodies to defend against infections. Karikó and Weissman partnered with Pfizer and BioNTech to create the COVID-19 vaccine using this innovative approach.

11. Kizzmekia Corbett // COVID-19

Kizzmekia Corbett, an immunologist at the National Institutes of Health’s Vaccine Research Center, played a pivotal role in the development of Moderna's mRNA-based vaccine for COVID-19. Her research explores how coronaviruses infect their hosts, and she focuses on creating vaccine strategies that are not only quick but also reliable and broadly applicable. In a lecture at NIH last December, she emphasized her commitment to addressing vaccine hesitancy, often engaging with communities of color to explain the science behind the COVID-19 vaccines.