When the coronavirus outbreak was spreading rapidly in the United States, one particular term called the “herd immunity” was being used widely. We all have probably heard of it while watching the news or while reading the newspaper.

Today, we are going to discuss the concept of herd immunity, it’s role in the spread of diseases, and whether we can achieve it with COVID-19 or not?

Introduction to Herd Immunity

When most of the population of a community is immune against infectious disease (either through vaccinations or by recovering after contracting the disease), it provides herd protection to even those who are not immune to the disease.

Most often, herd immunity (also known as community immunity or herd protection or group protection) is to provide protection against infectious diseases to all those who cannot be vaccinated. Such individuals are too weak and vaccinations can make them sick. They include:

  • Children who are too young to be vaccinated

  • People with immune system problems

  • Immuno-compromised individuals

Generally, about 70% - 90% of a population has to be immune to achieve herd immunity. 

Role of herd immunity in curbing the spread of diseases

Herd immunity can effectively prevent the transmitting of a disease. Let’s see how. 

For example, if 70% of a population is vaccinated for a virus, nearly every 3 out of 5 people who encounter an infected person will not catch the infection. In this way, the spread of infectious diseases can be kept under control. However, note that the spread of infection depends on how contagious it is.

Has herd immunity worked previously?

Herd immunity has worked wonders for some illnesses like measles, polio, and chickenpox in the USA and for swine flu in Norway. 

The percentage of a population that needs to be immune to achieve herd immunity varies from disease to disease. While for some diseases, 40% of a population needs to be immune, for others, herd immunity will kick in only after 90% of the population is immune.

Herd immunity vs Vaccination

  • Herd immunity is not the best alternative to getting vaccinated for most healthy individuals.

  • Vaccination is the only protection against some diseases like tetanus (caused by bacteria and not spread by an infected person).

  • Getting yourself and your family vaccinated is the best way to stay immune and to practice herd immunity. Herd immunity might not provide 100% protection against all diseases, but it can surely curb its spread.

Herd immunity and COVID-19

As of today, there are no vaccines for SARS-CoV-2, the virus responsible for COVID-19. Currently, achieving herd immunity for COVID-19 is not possible. Only after a significant portion of the world’s population is vaccinated against COVID-19 in the future, herd immunity will be able to provide protection to the remaining.

Till then, we all must be mindful and practice social distancing and frequent hand washing.

Stay safe, stay healthy!