What is Herd Immunity?
This is known to be a form of protection from diseases that are infectious indirectly. This form of immunity happens when a bigger percentage of a given population over time becomes immune to an infection. In this respect, this occurrence ascertains that the population is provided with a measure of protection for those among it who are not immune. It is also referred to as social immunity, population immunity, community immunity or herd effect. The term herd immunity is recognized as a naturally occurring phenomenon which was discovered nearly a century ago. It was observed then that after a notable number of children became immune to measles which was a deadly disease and the number of new infections reduced for a while even among children considers to be susceptible.
How Does Herd Immunity Work?
Herd immunity only works for those infections that are contagious, meaning that they can be transmitted from one person to another. In this respect, Tetanus is an infectious disease but it is not contagious hence herd immunity cannot work. When a large percentage of a given population is immune, there occurs the possibility that the chains of infection encounter disruption. As a result, it either halts or reduces the progression of the infection. It is observed that, the greater the number of people within the society who are immune to a given infection, the smaller the chances that those who are not immune will interact with an individual who is infectious. Mass vaccination, which is an artificial method of protecting against infection has become common and has shown a high rate of success in the prevention of spread for multiple diseases. The high levels of immunity in one given age group can give rise to herd immunity for other age groups within a population. Therefore, vaccinating adults against a certain incidence of disease in babies who are too young to be vaccinated can alleviate risk of complications from the given disease. When it comes to sexually transmitted infections, high levels of immunity in one sex such as female increases heard immunity for both males and females.
Link between Individual Immunity and Herd Immunity
Individual immunity is usually got though undergoing recovery from a natural infection or through vaccination which is an artificial method. It has been established that some individuals are not in a position to become immune and in these cases, herd immunity is a significant method of protection. The moment a given threshold has been attained, herd immunity progressively gets rid of an infection from a population. Scientific studies have shown that, when this elimination is attained globally, the possibility of a permanent reduction is high and can bring down the number of infections to zero which is known as eradication.
Researchers have noted that emerging controversies surrounding vaccination and courses opposing vaccination have made herd immunity not to occur or be eliminated altogether in given societies. This has consequently made preventable diseases to persist in these societies or return after a certain period of time.