What Is Herd Immunity?
It is a form of Community or group protection from infectious diseases which occurs when the majority of the population has become immune to that infection. It can happen in two ways:
- Natural Immunity – Many people are exposed to the disease and with time become immune to it.
- Vaccination – People are vaccinated to get immunity against the disease
How Does Herd Immunity Work?
1. Herd immunity is reached when the majority of a population (70% – 90%) becomes immune to an infectious disease, either because they have become infected and recovered or through vaccination.
2. Viral Infections often spread through person-to-person. When most of the people are healthy, the chain of infection is broken because most people don’t get or transmit the infection.
3. It helps in protecting people who aren’t vaccinated or have low functioning immune systems.
Levels of Herd Immunity
There are 3 Levels to Herd Immunity, that speak of it’s extent and prevalence:
- Red: Not Immunised, Weak Immune System
- Yellow: Not Immunised, but still Healthy
- Green: Immunised and Healthy
Discussing Scenarios of Herd Immunity
No one is immunised initially, and with a handful of infected individuals, the contagious disease starts to spread throughout the population.
Some people get immunised and the contagious disease spreads throughout the population.
Most of the people get immunised, and this forms a protective ring around those who are still susceptible to disease. Spread is contained.
The World Health Organisation Executive Director for Health Emergencies, Mike Ryan, warns that serological studies were presenting increasing evidence that a herd immunity approach to mitigating the effects of further waves of infection would not be effective.
Sweden Trial of Herd Immunity
Early on in the Coronavirus Pandemic, Sweden decided to forgo the lockdown in the hope of achieving broad immunity to the Coronavirus. But now, Sweden’s mortality rate is unfortunately quite high and more than most of the countries that exercised a Lockdown.
Scientists estimate that herd immunity for COVID-19 is reached when 70 – 90% of the population becomes immune to a virus, either by becoming infected or by getting a protective vaccine.
Sweden is nowhere near that goal, according to the Tests carried out by Sweden’s Public Health Agency. The agency tested 1,118 residents of Stockholm over a period of 1 week in the end of April, 2020. Only 7.3% people had developed the antibodies needed to fight the disease.
Heavily Populated India
In heavily populated countries like India, research studies say that Herd Immunity is a huge gamble as the experiment results could go either way.
Renowned Immunologist and Cell Biologist Dipyaman Ganguly was heard quoting “This coronavirus is not going anywhere. Viruses don’t go anywhere. They may become weak but its strand remains. The virus will keep infecting people until a large population develops immunity against it. Since developing a vaccine for COVID-19 is not an easy task and it is unlikely that we will get one soon, the only hope that remains is that of herd immunity and it is bound to happen. The virus is going infect a large number of populations in India. When a large number of people get infected, their bodies will develop natural immunity. They will stop the virus from spreading further by breaking the chain of infections transmitted from one person to another. Since I am closely monitoring the situation, I am sure that we are moving towards herd immunity.”