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
Officials also said the metro falls short of having herd immunity from the disease.
—Pj Green, Kansas City Star, 19 Apr. 2025
The seven separate outbreaks, defined as 3 or more related cases by the CDC, have been largely attributed to declining MMR vaccination rates, which have resulted in a growing number of states losing herd immunity status.
—Mary Walrath-Holdridge, USA Today, 17 Apr. 2025
Under this threshold, herd immunity can no longer limit spread enough to protect the unvaccinated.
—Sarah Zhang, The Atlantic, 7 Apr. 2025
Twenty-five years ago, nationwide vaccination efforts had virtually eliminated the disease in the United States by achieving vaccination rates of 95% across the country, establishing herd immunity and preventing the disease from spreading.
—Dr. Josh Green, CNN Money, 5 Apr. 2025
See All Example Sentences for herd immunity
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Pj Green, Kansas City Star, 19 Apr. 2025
The seven separate outbreaks, defined as 3 or more related cases by the CDC, have been largely attributed to declining MMR vaccination rates, which have resulted in a growing number of states losing herd immunity status.
—Mary Walrath-Holdridge, USA Today, 17 Apr. 2025
Under this threshold, herd immunity can no longer limit spread enough to protect the unvaccinated.
—Sarah Zhang, The Atlantic, 7 Apr. 2025
Twenty-five years ago, nationwide vaccination efforts had virtually eliminated the disease in the United States by achieving vaccination rates of 95% across the country, establishing herd immunity and preventing the disease from spreading.
—Dr. Josh Green, CNN Money, 5 Apr. 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 25 Apr. 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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