What term is used to describe a significant number of individuals that are immune to a given pathogen, which protect the entire population?
Select one: a. herd immunity b. active immunity c. passive immunity d. proportional immunity e. indirect immunity
The correct answer and explanation is:
The correct answer is a. herd immunity.
Explanation:
Herd immunity, also known as community immunity, occurs when a large portion of a population becomes immune to a specific infectious disease, either through vaccination or previous infection. This high level of immunity within a population makes the spread of the disease less likely, as there are fewer susceptible individuals to pass the pathogen on. The immunity of the majority provides indirect protection to those who are not immune, such as individuals who cannot be vaccinated for medical reasons, or those with compromised immune systems.
The concept of herd immunity is especially important in the context of vaccination programs. Vaccines, by boosting immunity in a large proportion of the population, help reduce the overall amount of the pathogen available to spread, which in turn helps protect individuals who are not vaccinated or cannot be vaccinated.
For example, in the case of diseases like measles or polio, achieving herd immunity through widespread vaccination can eventually lead to the elimination of the disease from a population. If enough individuals are immune, the pathogen has fewer opportunities to spread, thereby indirectly protecting those who are vulnerable, such as infants, the elderly, and immunocompromised individuals.
Herd immunity can be considered a form of indirect protection because it does not rely on every individual being immune, but rather on enough people being immune to make transmission unlikely. The level of vaccination required to achieve herd immunity depends on the disease in question and its contagiousness, measured by the basic reproduction number (R0).
In summary, herd immunity is crucial for preventing the spread of infectious diseases and protecting vulnerable populations, and it is a key strategy in public health efforts to control outbreaks.