What does 'herd immunity' refer to?

Herd immunity refers to the phenomenon where a significant portion of a population becomes immune to an infectious disease, either through vaccination or previous infections, thereby providing indirect protection to those who are not immune. When enough individuals are vaccinated, the spread of the disease is hindered, leading to a decrease in transmission rates within the community. This is particularly vital for protecting vulnerable groups who may not be able to receive vaccines themselves due to medical reasons, such as infants, the elderly, or individuals with compromised immune systems.

The concept emphasizes that collective immunity achieved through vaccination can lead to the eradication or control of diseases, making it a crucial public health goal. In this context, while individual resistance and natural immunity are important, they do not capture the essence of how herd immunity protects the wider community through vaccination efforts.