The herd immunity theory was co-opted during the 1930s from its original concept and is being heavily promoted today as gospel by the mainstream press and allopathic doctors.

Originally, herd immunity sprang from the idea that a family or community (the 'herd') obtained resistance and immunity to an infection by being exposed to it through natural contact. It was subsequently plagiarized by the mainstream medical profession to associate herd immunity with the widespread deployment of vaccines ('inoculations' or 'immunizations').

Medical herd immunity created artificially (such as with the administration of the measles vaccine) provides a person with limited 'protection' that disappears within 2-10 years, while natural herd immunity obtained through exposure to the bacteria or virus in the wild can last a lifetime.

Mothers who go through the experience of contracting the wild form of measles or chicken pox as children are able to pass on those antibodies to their newborns when their babies are most vulnerable, while other mothers who received vaccines that suppressed those infections are not able to transfer any antibodies.
-NW

The Misunderstood Theory of Herd Immunity
by Marco Cáceres | The Vaccine Reaction
Published June 20, 2015

[snip]

In an epidemiological review paper titled “Herd Immunity: History, Theory, Practice,” written by Paul E. M. Fine and published in 1993, the author notes that the first “published use” of the term herd immunity “appears to have been” in a paper titled “The spread of bacterial infection: the problem of herd immunity,” written by W. W. C. Topley and G. S. Wilson and published in 1923.

From Fine’s paper, it seems that the theory of herd immunity was originally developed based on some observations with mice and some “simple mathematical formulations,” but the paper is unclear about whether the theory was ever validated through some of sort scientific peer review process—as is commonly the case with theories that eventually come to be widely accepted as “proven science.”1 2

In 1933, Dr. Arthur W. Hedrich, a health officer in Chicago, IL observed that during 1900-1930, outbreaks of measles in Boston, MA appeared to be suppressed when 68% of the children contracted the virus. Subsequently in the 1930s, Dr. Hedrich observed that after 55 percent of the child population of Baltimore, MD acquired measles, the rest of the population appeared to be protected. It was that observation that formed the basis for mass vaccination campaigns.