Herd Immunity

 

Why in Discussion?

Recently, the world's scientists have hinted at adopting the option of Herd Immunity to deal with the rapidly spreading COVID-19 challenge.

 

What is Herd Immunity?

Herd immunity means "to prevent the spread of an infectious disease through the development of immunity in a certain percentage of people of a society or group."

 

The concept behind adopting this process is that if enough people are immunized, the chain of spread of the disease in a society or group can be broken and thus the disease can be prevented from reaching those who are most at risk or whose immunity is weak.

 

How Does Herd Immunity Work?

Epidemiologists use a standard known as 'Basic Reproductive Number-R0' to estimate the spread of an infectious disease and the immune range required for it.

 

It tells how many other people can get infected with that disease when they come in contact with a single case or patient.

 

R0 is greater than 1 means that one person can infect another person as well.

 

According to scientific evidence, one person with Measles infects 12-18 other people. Whereas a person suffering from Influenza can infect about 1-4 persons.

 

Any Infection can Spread in Three Ways in a Society / Group: 

• The first situation where no person in the group is vaccinated. So if two cases of R0 with 1 coefficient are found in such a group, then that whole community can get infected.

 

• In the second case, if only few people of a group have been vaccinated, then other people of that group may be infected, except those.

 

• But if sufficient people in a group are immune, then in such a situation, only those people of the group who are very weak or who do not have strong immunity. This seems incomplete

 

How to Get Herd Immunity?

According to experts, the success of herd immunity depends on many factors, such as the effect of the vaccine to prevent infection, the duration of infection and the part of the group that is responsible for the spread of the infection.

 

It is determined by a fixed number in a generic form, which is called the Herd Immunity Threshold. It refers to the number of people on whom the infection cannot affect and communicate.

 

The range is 80–85% for polio while 95% for measles. Based on the currently available data, this limit for COVID-19 is about 60% that means 60% of the group of people are required to be immunized against COVID-19 in a group to get herd immunity.

 

Herd Immunity Challenges in Dealing with COVID-19 –

According to experts, it will be risky to allow more people from society to get infected with COVID-19 to get immunity in the absence of more information.

 

The development of immunity to COVID-19 in such large amounts can take a long time, which can lead to many risks, especially when we know that people with co-morbidities like heart disease and high blood pressure are most vulnerable to this infection.

 

In this process, immunity can develop in those people who once become infected can get rid of infection. But in the context of COVID-19, there is no evidence of success of this process nor can it be ensured that once cured, no person will be infected with the disease again. 

 

 

 

References:

Drishti IAS (Internet)

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