vaccine

American  

[vak-seen, vak-seen, -sin] / vækˈsin, ˈvæk sin, -sɪn /

noun

vaccines plural

1. any preventive preparation used to stimulate the body’s immune response against a specific disease, using either messenger RNA or killed or weakened bacteria or viruses to prepare the body to recognize a disease and produce antibodies.

2. (no longer in technical use) the virus of cowpox, used in vaccination, obtained from pox vesicles of a cow or person.

3. a software program that helps to protect against computer viruses, as by detecting them and warning the user.

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adjective

1. of or relating to vaccination.

2. of or relating to vaccinia.

3. of, relating to, or derived from cows.

vaccine British  

/ ˈvæksiːn /

noun

1. a suspension of dead, attenuated, or otherwise modified microorganisms (viruses, bacteria, or rickettsiae) for inoculation to produce immunity to a disease by stimulating the production of antibodies

2. (originally) a preparation of the virus of cowpox taken from infected cows and inoculated in humans to produce immunity to smallpox

3. (modifier) of or relating to vaccination or vaccinia

4. computing a piece of software designed to detect and remove computer viruses from a system

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vaccine Scientific  

/ văk-sēn′ /

1. A preparation of a weakened or killed pathogen, such as a bacterium or virus, or of a portion of the pathogen's structure, that stimulates immune cells to recognize and attack it, especially through antibody production. Most vaccines are given orally or by intramuscular or subcutaneous injection.

2. See Note at Jenner

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vaccine Cultural  

1. A substance prepared from dead or living microorganisms that is introduced into the body through inoculation. The vaccine causes the development of antibodies, which produce immunity to the disease caused by the microorganism.

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Usage

What does vaccine mean? A vaccine is a substance introduced into someone’s body to prevent them from getting a specific disease. It usually consists of a small amount of a killed, weakened, or otherwise modified version of a disease (such as a virus or bacterium). Vaccines work by allowing your immune system to develop defenses against that disease, called antibodies, so they can destroy it if it ever enters your body again. Common vaccines include ones for strains of the flu, polio, hepatitis A, hepatitis B, tetanus, diphtheria, whooping cough, chickenpox, measles, mumps, and rubella. There are many others. Example: The polio vaccine has saved millions of people.

Closer Look

In the 1950s, polio epidemics left thousands of children with permanent physical disabilities. Today, infants are given a vaccine to prevent infection with the polio virus. That vaccine, like most others, works by stimulating the body's immune system to produce antibodies that destroy pathogens. Scientists usually prepare vaccines by taking a sample of the pathogen and destroying or weakening it with heat or chemicals. The inactivated or attenuated pathogen loses its ability to cause serious illness but is still able to stimulate antibody production, thereby conferring immunity. The Salk polio vaccine contains “killed” virus, while the Sabin polio vaccine contains weakened “live” poliovirus. (Many scientists no longer consider viruses to be living organisms) Scientists are also able to change the structure of viruses and bacteria at the molecular level, altering DNA so that the potential of the vaccine to cause disease is decreased. New vaccines containing harmless bits of DNA have also been developed.

Other Word Forms

Derived Forms

• provaccine
  adjective

Inflected Forms

Nouns

• vaccines
  plural

Etymology

Origin of vaccine

< New Latin ( variolae ) vaccīnae cowpox (in title of E. Jenner's treatise of 1798), equivalent to vacc ( a ) cow + -īnae, feminine plural of -īnus -ine ¹

Explanation

To prevent you from getting sick, a doctor will give you a shot with a vaccine in it, which is a mixture that teaches your body how to fight against viruses and diseases. It’s fascinating how vaccines work. A dead or really weak strain of a virus is injected into your body, and your system creates antibodies specifically designed to fight that particular virus. Once your body learns how to make those antibodies, you become immune to the virus, and it can’t make you sick. The word comes from the Latin vacca, meaning “cow,” because in 1796 a doctor used “cow pox” viruses to create a vaccine to prevent smallpox. Thank you, cows.

Example Sentences

See Examples For:

vaccine vaccines

Recent outbreaks have taken root in places where vaccine hesitancy is common, including among Mennonites in Texas and evangelical Slavs in South Carolina.

From Slate ● Jul. 24, 2026

During the 2024-25 school year, just 92.5% of kindergartners had received the measles vaccine, down from 95.2% during the 2019-20 school year, according to the CDC.

From Los Angeles Times ● Jul. 24, 2026

In Idaho, 78.5% of kindergartners received the MMR vaccine ahead of the 2024-25 school year—the lowest share of any state.

From The Wall Street Journal ● Jul. 24, 2026

She explained how they would confirm that the vaccine was effective at protecting people.

From BBC ● Jul. 24, 2026

Then they develop an equivalent vaccine and cure for it.

From "Legend" by Marie Lu

Safe and effective vaccines have been widely available since the 1960s; by 2000, the U.S. declared measles eliminated here.

From Slate ● Jul. 24, 2026

There are four vaccines in development against the Bundibugyo species which has triggered the outbreak, but this is the first to enter human trials.

From BBC ● Jul. 24, 2026

Health officials are encouraging parents to plan now for updating their kids’ vaccines, with the new school year only a few weeks away.

From Los Angeles Times ● Jul. 23, 2026

A clearer view of this takeover could help scientists develop more effective flu vaccines and antiviral drugs.

From Science Daily ● Jul. 21, 2026

Without those tissues, we would have no tests for diseases like hepatitis and HIV; no vaccines for rabies, smallpox, measles; none of the promising new drugs for leukemia, breast cancer, colon cancer.

From "The Immortal Life of Henrietta Lacks" by Rebecca Skloot

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