In "Fox Nation 101: Making Vaccines," one of the top infectious disease physicians in the United States explained what vaccines are, how this medical technology has saved countless lives and delved into the fascinating history of the discovery of vaccines.

It all started with a Scottish country doctor named Edward Jenner in the late 1790s, explained Dr. Amesh Adalja, a senior scholar at the Johns Hopkins University Center for Health Security.

Jenner discovered that milkmaids were seemingly immune to smallpox, which is an infectious disease that regularly ravaged populations in The United Kingdom and around the world.

"At that time there was nothing called vaccination," said Adalja. "There was something called variolation, which was a variation of vaccination. But it really involved taking the actual material of smallpox and scratching it into your skin so that you would get a mild case and be protected from a severe case."

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Dr. Jenner realized variolations for smallpox were ineffective for the milkmaids because they had already developed an immunity to smallpox through their exposure to cowpox.

"He really took that and developed what was the first vaccine," said Adalja. "In essence, what a vaccine does is it takes some part or some portion of whatever you want to vaccinate against and gives it to your body."

"Your immune system sees that substance and then develops antibodies or these specialized proteins that can bind to the target and allow that to be cleared from your body and basically render you impervious for the most part to some of these pathogens."

The French biologist and chemist, Louis Pasteur took Jenner's discovery an enormous step forward several decades later with the creation of a rabies vaccine for humans.

"[Pasteur] really cemented this idea that you could find an organism that you wanted to vaccinate against, make a vaccine against it and that problem would no longer be something that haunted humanity," noted Adalja.

In a nod to the advances made by Jenner, Pasteur named this newly created medical technology vaccination. 

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"The word vaccine actually comes from the Latin word for cow," said Adalja, "In honor of Jenner, Louis Pasteur named the technology, vaccination, even though the rabies vaccine had nothing to do with the cow or cowpox."

"From smallpox to polio to pneumonia-causing bacteria to influenza to yellow fever, there are so many vaccines that make our life so much better," concluded Adalja. "You can really just look at civilization and measure what the impact of vaccines have been in terms of lifespan, in terms of infant mortality, in terms of child mortality. And I think that they really have to be thought of as one of the greatest technological advances."

To learn more from Dr. Adalja, including his thoughts on the potential promise of a COVID-19 vaccine and persistent myths about vaccines, go to Fox Nation and watch "Fox Nation 101: Making Vaccines."

You can also learn more from the "Fox Nation 101" series by watching "Pandemics and Epidemics 101," with Dr. Nicole Saphier, who is a full-time practicing physician at Memorial Sloan Kettering Cancer Center and a Fox News contributor.

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