HERD IMMUNITY

HERD IMMUNITY

Subject: Science & tech

Context: Despite serosurveys indicating many metros such as Delhi, Mumbai, and Pune having reached high levels of immunity, the same cities are seeing an explosive surge.

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.