herd immunity

herd immunity definition - medical

herd immunity (hûrd)

noun
  1. Resistance to the spread of infectious disease in a group because susceptible members are few, making transmission from an infected member unlikely.
  2. The immunologic status of a population, determined by the ratio of resistant to susceptible members and their distribution.

The American Heritage® Medical Dictionary Copyright © 2009 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

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