The origin of the word vaccine is Latin. It comes from vacca (“cow”) and the related word vaccine (“from cows”). (The Latin pronunciation for vaccine is different than in English.)

Here’s how Merriam-Webster defines vaccine:

a preparation of killed microorganisms, living attenuated organisms, or living fully virulent organisms that is administered to produce or artificially increase immunity to a particular disease.

“Hold on,” you’re saying. “I don’t see anything in that definition about cows.”

Origin of the Word Vaccine: The Bovine Connection to Human Health

Well, a bit of medical history is in order when we talk about the origin of the word vaccine. In the late 1700s, English physician Edward Jenner made an interesting find.

He noticed that milkmaids who had contracted cowpox—a disease that causes blisters to form on a cow’s udders—did not contract smallpox.

So he did a test. He exposed over a dozen farm workers to smallpox, all of whom had previously had cowpox. (Cowpox causes only minor blistering in humans.)

The result? None of the workers who had had cowpox and were then exposed to smallpox developed the latter. In other words, if you had been exposed to cowpox, you were immune to smallpox.

In 1796, Jenner ran an unethical but world-changing experiment. He infected a boy with cowpox on purpose, then exposed him to the smallpox virus. The boy didn’t get sick.

Jenner called his invention “vaccination” and published his findings two years later.

The Impact of Vaccines

Just how valuable was the good doctor’s experiment? Well, by 1820, millions of people had been vaccinated. The death rate from smallpox had dropped by half. In fact, smallpox was declared eradicated in 1979.

The origin of the word vaccine should be no surprise for native speakers of Romance languages. (Latin gave birth to Romance languages, after all.) Take a look at the following list of words that mean “cow”:

• vaca (Spanish and Portuguese)
• vacca (Italian)
• vache (French)
• vacă (Romanian)

So the next time you drive past a dairy farm, thank the cows.

Sources and additional reading:
“Edward Jenner,” Wikipedia.
“What the hell’s wrong with us? Autism, vaccines and why some people believe Jenny McCarthy over every doctor,” Salon.com.
“Vaccination,” Online Etymological Dictionary.
“Vaccine,” Merriam-Webster.

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