Herd immunity – solution to viral infection????

Before moving directly to our topic we need to understand some basic concepts like immunity and its types, what is disease and its type.

What is immunity?

It is body’s defence system which work against the foreign pathogen. Pathogen may be a virus or bacteria or protozoa.

Innate immunity?

It is general immunity or we can say it is non specific. Once the body detects any forgein particle (virus/bacteria)the first response from body is in the form of innate immunity.

Adaptive immunity?

It is the specific type of immunity, it is developed against specific pahogen. Body develops the antibodies to fight against pathogen. One very important point to remember is this type of immunity is that it has memory. Which means if the body is infected with same pathogen in the future then it has a memory of the infection and in turn it immediately prepares antibodies. Our topic is related to the adaptive immunity.


The word disease itself means dis-ease means discomfort. A condition where the forgein particle causes discomfort in our system is called disease.

Contagious disease?

A disease which spreads from person to person. The speed of spread can vary depending upon different conditions.

Infectious disease?

A disease caused by infective agent like bacteria or virus.it will not spread from person to person.

From above two concept we can say that every contagious disease is infectious disease but every infectious disease is not contagious disease.As per our topic i.e. herd immunity is concerned, it is the term related to only contagious disease.

what is herd immunity?

When majority of population is immune to the contagious disease which in turn provides protection to those who are not immune to that disease. Means as the percentage of immune person in the population increases the chance of the spread of the disease drops drastically.

Take the example,
If 80% of a population is immune to a virus, 8 out of 10 people who encounter someone with the disease wont get sick and in turn wont spread the disease any further. In this manner the spread of the contagious disease is kept under control.


Herd immunity was first recognized as a naturally occurring phenomenon in the 1930s when A.W.Hedrich published the research paper on measles.
Polio, Mumps, Measles and Chickenpox are examples of diseases which are eradicated by achieving herd immunity.

Ways to achieve herd immunity?

There are 2 ways to achieve this.

1) Through vaccination – vaccination creates the immune response against the particular pathogen.So by giving the vaccine to some of the population we can control the spread of that disease.

Example-lets assume there are 100 people in the population. We have given a vaccine to 70 persons out of these 100. These vaccinated 70 persons chances to spread the disease is less so we can say that we have achieved the herd immunity for that particular disease.

2) Natural way(without vaccination)-sometimes it is very difficult to make a vaccine particulerly in the case of virus. Reason is the mutation that happens in the virus. In this case persons get infected, some of them recovers and developed a immune system. But we have to pay the price as there are many persons who are immunologically weak for them this situation is detrimental. So we can say that it is natures own way of controlling the contagious disease.

Covid 19 and herd immunity relation.

As we all know till now we don’t have any vaccine for COVID 19.so there are 2 options in front of us to control the spread,

1) Wait till the vaccines is prepared so that by vaccination we can trigger the adaptive immunity of the population.

2) Relax the lockdown and allow them to roam so the population gets infected by the virus and in turn they will generate the immune response for that virus, but we may have to sacrifice many lives specially old age and infants which have weak immune system.


We can say that if we achieve a herd immunity through vaccination it will be a great achievement, but if we have to opt for the other option(natural way) then we have to surrender many lives. Recently WHO also warned the countries that if they are aiming to achieve the herd immunity naturally then it will be dangerous. Choice is yours?

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