What is the concept of herd immunity?

Herd immunity refers to a form of indirect protection from infectious diseases that occurs when a significant portion of a population becomes immune, either through vaccination or previous infections. This majority immune status makes it difficult for the disease to spread, thereby providing a level of protection for individuals who are not immune, such as those who cannot be vaccinated for medical reasons or those for whom the vaccine was not effective.

When a community reaches herd immunity, the likelihood of an outbreak diminishes significantly because there are fewer hosts for the pathogen to infect. This concept is crucial in public health as it helps control diseases and protect vulnerable populations. Herd immunity does not require every individual to be vaccinated or immune, but rather a large enough percentage of the population must be immune to slow down or halt the transmission of the disease.

In contrast, protection achieved through individual vaccination is insufficient for preventing widespread outbreaks on its own without the community being largely immune. Increased susceptibility among the community clearly contradicts the principle of herd immunity, as it implies a lack of sufficient immune individuals. Finally, while complete eradication of a pathogen is an ideal goal, it is not synonymous with herd immunity, as herd immunity focuses on preventing disease transmission rather than eliminating a pathogen entirely from the population.