Analysis: A short history of herd immunity
News // Local
Jordan Fenster
Sep. 25, 2020 Updated: Sep. 25, 2020 12:21 p.m.
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Why is it called "herd immunity," do you think?
A recent article in the journal Lancet offers a fascinating history of the phrase and, as it turns out, it's called "herd immunity" because it originated in reference to cows.
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Cows decorated with bells and flowers rest after the annual ceremonial "cattle drive" (Almabtrieb), on September 18, 2020 at Gramai-Alm in Tyrol's Karwendel Alpine nature park.
In the 1910s, a disease was spreading around U.S. cattle farms causing "epidemics of spontaneous miscarriage" (they called it "abortion disease"), and farmers were destroying cows as a way to solve the problem.
Enter veterinarian George Potter who, writing in the Journal of the American Veterinary Medical Association, apparently coined the phrase "herd immunity."
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A lab worker tries to isolate the presence of Coronavirus during a swab test process in the Molecular biology laboratory of the Ospedale Niguarda, on March 05, 2020 in Milan, Italy.
"Abortion disease may be likened to a fire, which, if new fuel is not constantly added, soon dies down," Potter wrote. "Herd immunity is developed, therefore, by retaining the immune cows, raising the calves, and avoiding the introduction of foreign cattle."
A few years later, bacteriologist W.W.C. Topley did some experiments on mice and wrote about the results. When the mice stopped catching the introduced illness, Topley said they had gained "herd immunity."
Topley thought the idea might also apply to children and in 1924, Sheldon Dudley, a professor of pathology at the Royal Naval Medical School, tested the concept at the Royal Hospital School in Greenwich, where there was a diphtheria outbreak.
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Clinical nurse has a blood sample taken by a clinical staff member at Sir Charles Gairdner hospital on April 20, 2020 in Perth, Australia.
"I will now consider the community, or the herd," Dudley wrote in 1929. "Nations may be divided into urban or rural herds. Or we can contrast the shoregoing herd with the sailor herd, or herds dwelling in hospitals can be compared with those who live in mental hospitals."
By the 1930s, the idea of herd immunity was considered as a way to handle influenza, polio, smallpox and typhoid, among other diseases, but thinking began to shift in the 1950s when vaccines became available.
Most recently, commentators in Lancet have argued that, considering the fact that COVID-19 antibodies might not actually provide protection from the virus, "any proposed approach to achieve herd immunity through natural infection is not only highly unethical, but also unachievable."