Herd immunity

Subject: Science and tech

Context:

Recent study found that herd immunity threshold (HIT) required to prevent a resurgence of SARS-CoV-2 (COVID-19) is in excess of 50 per cent for any epidemiological setting.

Concept:

Herd immunity happens when so many people in a community become immune to an infectious disease that it stops the disease from spreading. This can happen in two ways:

• Many people contract the disease and in time build up an immune response to it (natural immunity).
• Many people are vaccinated against the disease to achieve immunity.

When a large percentage of the population becomes immune to a disease, the spread of that disease slows down or stops. Many viral and bacterial infections spread from person to person. This chain is broken when most people don’t get or transmit the infection. This helps protect people who aren’t vaccinated or who have low functioning immune systems and may develop an infection more easily