As you all know, the only way to prevent contracting any disease, including COVID, is to develop strong immunity against it. Immunity is a series of steps your body takes to destroy a threat. Basically, when a foreign body called antigen enters your system, your body activates immunity cells called B Lymphocytes. B lymphocytes produce antibodies and send both the antibodies as well as T lymphocytes to attack and destroy the threat. The antibodies stay in your system and if that particular germ enters your body again, you won’t be affected. 

Now this concept is at the core of herd immunity. We have often heard that herd immunity is the only way to stop the COVID pandemic. But what is herd immunity and will India be able to develop it? 

What is herd immunity?

When a huge percentage of the population has developed antibodies against a disease, then that population has herd immunity. It is also termed as mass immunity. When herd immunity is developed, an outbreak dies out gradually. Even though some people may not have the required immunity, the population or herd is immune. Even if the herd is exposed to the disease again, the rate of infection would be very low. 

Herd immunity is very important in diseases like covid which was once an epidemic as it makes it possible to protect the population from a disease including the ones who are very vulnerable and can’t be vaccinated like the immunocompromised and the newborns.

Dr. Ashish Bajaj, M.B.B.S., M.D.

How does a country acquire herd immunity?

There are two ways to attain herd immunity-

• Exposure

As we explained earlier, when a virus enters your body, your immunity will produce antibodies to kill the virus. Once you’ve contracted the infection, your body will remember the antigens, and the risk of contracting again is very low.  

If most of the people of the country have fallen sick because of COVID, they will develop immunity against it. And fresh exposure would not be a threat to them. Once they are immune, they will not pass on the disease to people of that country who have not developed an immunity. So even non-immune people would be relatively safe.

• Immunization through vaccines

Vaccines introduce the antigen of the virus into the body in very small doses. You will not fall sick, but your immunity will become familiar with the antigen and develop antibodies. Herd immunity can be reached when the population has been vaccinated. 

I personally feel after 3 waves and millions of infections and crores of vaccination, India might have developed herd immunity. Unless a major mutation in virus is there, unlikely there will be another wave.

Dr. M.G. Kartheeka, MBBS, MD

Will herd immunity put an end to COVID?

Herd immunity through exposure will only slow down the rate of infection and the RO (number of people an infected person passes the disease to). It may take many months before COVID is wiped out if we rely on exposure to build immunity. Vaccination puts an immediate end to a pandemic.

Can India achieve herd immunity?

Most Indian doctors and healthcare experts are vehemently opposed to the idea of natural herd immunity by exposing people to COVID. Even epidemiologists never considered natural herd immunity as an effective way to end a pandemic like Small Pox or the Spanish Flu. 

Why are they so reluctant to let India acquire immunity through exposure? Because the risk is just too high. COVID is dangerous and has claimed millions of lives. Hundreds of thousands of people in our country have comorbidities such as diabetes, asthma, or hypertension, making a COVID infection lethal. 

Encouraging India to develop natural herd immunity would put the lives of these people in danger. Besides, studies have found that COVID antibodies last only for 5-7 months. 

However, developing herd immunity through vaccination is feasible. That is what epidemiologists have relied on in the past as well. Only when every single person has been vaccinated, India will acquire immunity. 

That is why doctors want you to stay at home as much as possible. Do not try to attain natural herd immunity as you will be risking the lives of your loved ones as well as your own. Follow the COVID protocol at all times.