herd immunity
noun
: a reduction in the risk of infection with a specific communicable disease (such as measles or influenza) that occurs when a significant proportion of the population has become immune to infection (as because of previous exposure or vaccination) so that susceptible individuals are much less likely to come in contact with infected individuals
… when the percentage of people vaccinated against a particular disease drops, herd immunity begins to fail.—
Katherine Hobson
Katherine HobsonSerious streptococcal disease does seem to be on the rise, however, perhaps because invasive strains are circulating against which we have not had time to develop much "herd immunity," as epidemiologists say.—Wayne Biddle
Wayne BiddleExamples of herd immunity in a Sentence
Recent Examples on the Web
Like most things in nature, however, herd immunity isn’t quite that clear-cut, said Dr. David Higgins, a pediatrician and preventive medicine specialist on the University of Colorado’s Anschutz Medical Campus.
—Meg Wingerter, Denver Post, 25 May 2025
When more than 95% of the people in a community are vaccinated, most people are protected through community immunity, often referred to as herd immunity, according to the U.S. Centers for Disease Control.
—Robert A. Cronkleton, Kansas City Star, 8 May 2025
Communities with vaccination rates below the 95% threshold necessary to maintain herd immunity become fertile ground for measles outbreaks.
—Dr. Josh Green, CNN Money, 5 Apr. 2025
Many took advantage of the policy, leaving the children in his practice well below the 95% threshold that experts say is needed to achieve herd immunity.
—Jenny Gold, Los Angeles Times, 27 Mar. 2025
See All Example Sentences for herd immunity
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Meg Wingerter, Denver Post, 25 May 2025
When more than 95% of the people in a community are vaccinated, most people are protected through community immunity, often referred to as herd immunity, according to the U.S. Centers for Disease Control.
—Robert A. Cronkleton, Kansas City Star, 8 May 2025
Communities with vaccination rates below the 95% threshold necessary to maintain herd immunity become fertile ground for measles outbreaks.
—Dr. Josh Green, CNN Money, 5 Apr. 2025
Many took advantage of the policy, leaving the children in his practice well below the 95% threshold that experts say is needed to achieve herd immunity.
—Jenny Gold, Los Angeles Times, 27 Mar. 2025
See All Example Sentences for herd immunity
Cite this Entry
“Herd immunity.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/herd%20immunity. Accessed 30 May. 2025.
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herd immunity
noun
: a reduction in the probability of infection that is held to apply to susceptible members of a population in which a significant proportion of the individuals are immune because the chance of coming in contact with an infected individual is less
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