Understanding the concept of Herd Immunity
Years ago life was so simple and pure. Growing crops and raising herds of cattle, sheep, and goats were the basis of economic activity. Hence the herds were the most precious holding of the human race. Theft, looting, attacks by the beasts like the wolf, tiger, etc. and diseases were the threats. The sickness was mainly because of infectious diseases. With the passage of time, Man learned to treat sick livestock in different ways.
The one famous method (tested over time) was to treat herds by mixing sick sheep with healthy ones. This way the virus was bound to spread through the whole herd. Some of the week ones got more effected facing death in the worst case. But the majority of the herd could get attuned to the virus, because of the strong immunity. It was the simple way out that the human race observed and like many other such experiences became part of folk wisdom. We can call it learning from nature.
Acceptance as a phenomenon
With the advancement of knowledge, the traditions and observations were taken into labs for better scientific examination and testing. Herd immunity was actually admitted as natural recourse to infectious diseases in 1930. It is also called community immunity, population immunity, or social immunity. The significant number of children was noted to become immune to measles, as the new infections started decreasing. Since then, the concept of Herd Immunity proved successful in preventing the spread of many infectious diseases.
How it works?
The phenomenon is taken as a safety measure against diseases where the majority holds strong immunity by way of vaccination or recovery from earlier infection. The masses having good immune health can provide a safety shield to the less immune lot. The concept goes fine with people of good health and strong immunity but the people suffering from other diseases and having weak immunity can still be infected.
There still are questions over this method. Achieving a certain thresh-hold of immune people the disease can be eliminated from the population. It is however is a gradual process. The results are not immediate. At the start, the infection graphs move upwards and gradually it starts dropping down with the increasing number of people recovering from the infection. Ultimately the stage of eradication is achieved over time, once the disease is permanently eliminated from the population.
The application of herd immunity
The question is if the concept is valid for all infectious diseases. The simple answer is a big NO. It is only applicable in the case of contagious diseases. These are the diseases that can be transmitted from one person to another. The infectious diseases which are not contagious, can not be treated by the phenomenon of herd immunity.