Word of the Day
April 28, 2020
Herd Immunity
A form of indirect protection from infectious disease that occurs when a sufficient percentage of a population has become immune through previous infections or vaccination, thereby reducing the likelihood of infection for individuals who lack immunity.
The term emerged in veterinary medicine in the early 20th century, derived from 'herd' (a group of animals) and 'immunity' (from Latin 'immunis' meaning exempt). It was first applied to human populations in the 1930s.
Usage Examples
- The 1918 pandemic showed that those who developed herd immunity in the first wave had up to 89 percent protection against death in the second wave.
- Public health officials debated whether pursuing herd immunity through natural infection or waiting for a vaccine was the appropriate strategy.
- Prolonged isolation policies may prevent the development of herd immunity, potentially making populations more vulnerable to future waves.
From the Show
The concept of herd immunity anchored the April 28th discussion as Pam Long argued that 1918 pandemic data demonstrated the protective value of developing natural immunity before a potentially more dangerous second wave.