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What is Herd Immunity? Can We Achieve it For Covid 19?

The Covid-19 pandemic has made all of us learn and use terms that were only used in documenting disease spread in populations. One of them is ‘ herd immunity’ which is often being used in conversations although the understanding is either incomplete or incorrect.  The broad thing that we have understood is that it is a crucial stage that we must accomplish for victory over coronavirus. Till now there is no medicine to cure corona infection. Our only weapon against it is our body’s capability to fight disease, which we call immunity.  Even as more and more people are getting immunized by exposure or vaccination, in India we are seeing a rebound of the contagious disease, much stronger than before. The likelihood of re-establishing normalcy still seems far away. 

When will we achieve herd immunity against coronavirus? Is it really achievable? If yes, how can we reach there faster? How many more lives will we lose?

Let’s try to understand all this. But before that,  we must understand the concept of herd immunity as a weapon against a highly contagious virus.

What is Herd Immunity

Immunity is disease resistance. When the body is exposed to infection(bacteria or virus), it tries to kill it by producing antibodies in the blood that match the cell structure of that bacteria or virus. For example, if you have had measles as a kid, or took a vaccine, your body has made antibodies against it. Now if you get exposed to a measles infection, you are safe, or “immune”.  When most people in a neighbourhood, community, or area develop strong resistance to a disease it gets eradicated. 

Herd immunity can be defined as a community’s resistance to a certain disease as a whole. It occurs when a significant percentage of the population becomes immune to a contagious disease so that there is low or negligible spread from one person to the other. 

What is this percentage? According to research, for the highly infectious covid 19 virus, it should be above 90%. For less infectious diseases, the percentage required is much lower. Many diseases have been totally eradicated in the past like this, such as measles, chickenpox, polio etc. However, still some communities remain in the world that do not have collective immunity against these and keep facing outbreaks from time to time. It is because they have low vaccine coverage. 

Since the coronavirus was new for all the populations across the world and super contagious, it met no resistance and spread like jungle fire. It has put life at standstill in most countries of the world. The likelihood of re-establishing normalcy still seems far away. 

To eradicate it, we need to achieve herd immunity, which can not be done unless each person joins in responsibly. How? Read on…

What will it take to achieve herd immunity for Corona?

There are two means of achieving complete herd immunity in the present pandemic. 

The first is natural immunity where people get exposed to the infection and develop antibodies. This is a very risky proposition.

The second is acquired immunization, the one you attain by receiving a preventive vaccine. 

Based on the data available, if the communities need to return to a normal life, they need to acquire at least 70% of their citizens to be immune. This figure also depends upon how interactive the community is, and how infectious is the corona variant ( some variants of coronavirus are found to be more potent than others).

When people reduce their degree of interaction through social distancing and masks etc, the infection ratio goes down.

However, when these norms are lifted, the virus mutates faster, and infection rates shoot up again. 

Presently, we are not at this stage in India that we can let go of the social distancing norms without risking people’s lives. Presently, the race is between the infection and the vaccine. 

What are the possibilities in achieving herd immunity

There are two best and worst scenarios. 

  1. The worst-case scenario is that we remove restrictions on social gatherings and mask-wearing before the vaccine reaches everyone. The virus will continue to infect people and claim lives. And that’s not it. The more people the virus infects, the more chances it has to mutate and become even stronger. It means an increase in transmission risk and a decrease in the effectiveness of vaccines. This is somewhat being played out in many states in India, including New Delhi and Maharashtra. 
  2. The best scenario would be that vaccination and social distancing are both applied parallel to each other with full force. Immunization through vaccines for contagious diseases is only effective when herd interaction is minimum. Each person in society must put in a strong effort for this scenario to play out. This way we may be able to beat the global epidemic and return to normal life before the winter season starts.

While both the possibilities are extreme, the most probable result would be somewhere in between. In the coming summer- spring season we will see a see-saw of rising and fall in corona cases. Because, when the cases fall and social distancing norms are relaxed(before all are vaccinated), the disease can rebound.

Will India ever get to herd immunity?

We can. Just as we discussed above, the parameters are vaccination and least interaction. Doctors are against the acquisition of herd immunity via exposure to the virus, as it is too risky. It puts the lives of a large percentage of people in danger, who suffer from comorbidities such as diabetes, hypertension or asthma. Besides, those antibodies last for five to seven months only.

Immunization via vaccination is a more feasible option to achieve herd immunity. For that, each person needs to be fully vaccinated.

This is precisely why the government and the medical fraternity wants you to remain at home, interact minimally with people, and not try to become immune through exposure. You will put the lives of your loved ones and the entire community at risk. 

What Role Do I Play?

You play a very big role. Even if you are immunized, you can still become a vehicle for the virus to move around. DO NOT BECOME A CARRIER OF THE CORONAVIRUS.

To attain herd immunity for the larger good of the society and the nation, 

  • Get vaccinated & encourage others, especially your employees
  • Interact minimum, stay at home 
  • Keep a physical distance
  • Wear a mask at all times 

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