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  5. Herd Immunity: What All You Need To Know?

The outbreak of COVID-19 pandemic [1] has highlighted the importance of immunity more than ever. By now, you must have come across the term ‘herd immunity’. Do you know how you can achieve it?

Herd immunity can cut down your health risks and others around you by providing indirect protection from infections. But can it put an end to the disease-causing infection?

Scroll down to know what herd immunity is and how it works.

What Is Herd Immunity?

When most of the population of the community acquire immunity to a disease, either through prior illness or vaccination, the spread of the disease to remaining non-immunized people in the community is likely to be very less. This type of immunity acquired by the non-immunized population is termed as ‘herd immunity’ or ‘community immunity’.

How Does Herd Immunity Function?

Contagious diseases are spread from one person to another person. But, when a person is immunized to a particular disease, the person’s body produces antibodies [2] against the pathogen when they contract. These antibodies fight and eliminate the germ strains from the body, which in turn stops the transmission of the disease from that person. This is the principle behind herd immunity, in which a large number of the population gets immunized to a disease.

This can happen either through vaccination at a large scale or when a major percentage of the population contracts the disease and develops antibodies. Thus, they break the chain of infection by limiting the transmission from them to the vulnerable sections of the community.

These vulnerable groups may include elders, infants, pregnant women, people with immunodeficiency, and those suffering from other health conditions. These people are at a higher risk in general as they may not be vaccinated or their immune system may fail to produce antibodies against the disease-causing pathogens.

“Typically, 50-90% of the population of a community needs to be immunized to attain herd immunity depending upon the contagiousness of a disease. This percentage is termed as herd immunity threshold,” says Dr. Zeel Gandhi, Chief Ayurvedic Doctor at Vedix.

Herd Immunity Examples In History

  • The USA achieved herd immunity against polio. Although the vaccine was developed in 1955, not every individual received it. However, on attaining the necessary herd immunity threshold, the cases were controlled. By 1979, polio was completely eradicated from the USA.
  • Similarly, India was declared as a polio-free country along with the rest of the south-east Asian countries in the year 2014 [3].
  • Smallpox is another deadly disease in human history that was eradicated in 1979. Here, herd immunity was achieved by extensive vaccination campaigns.
  • Norway developed at least partial herd immunity to swine flu through natural immunity and vaccinations.
  • Diseases such as measles, pertussis, and rubella have been in control and kept in low levels by maintaining the immune population proportion above the threshold.
  • In animals, rinderpest was completely eradicated through herd immunity in the year 2011.

herd immunity infographic vector illustration

The natural occurrence of herd immunity was discovered in the 1930s when the infection rate of measles dropped after a significant number of children were infected.

How To Get Herd Immunity Without A Vaccine?

Without a vaccine, herd immunity can be achieved when a large number of the population develops natural immunity to a specific disease. Natural immunity is attained by a person through disease contraction.

For example, if you had chickenpox once, then your body develops antibodies against the virus if contracted again. Thus, you are likely to not develop the disease again and thus prevent its spread to other people around you even though they are not immune to chickenpox.

However, achieving herd immunity through natural immunity is risky as contracting illness can become serious in some cases.

Pros & Cons Of Herd Immunity


  • Herd immunity is a great way to protect people who cannot get vaccinated. Infants and people with immunodeficiency should avoid certain vaccines as it may make them sick. Such people can get protected from infections with the help of herd immunity.
  • In certain diseases where vaccines are not developed yet or the efficacy of vaccines is not that great, herd immunity through natural immunity in resilient groups can help in protecting vulnerable groups.


  • Not every disease can be controlled by herd immunity. Diseases like tetanus are caused by environmental bacteria but do not spread through human transmission. In such cases, herd immunity does not work and vaccination is the only solution.

What Diseases Were Eradicated By Herd Immunity?

According to the world health organization, smallpox and rinderpest are the only diseases which were completely eradicated from the world by herd immunity till date [4].

Risks Of Herd Immunity

  • In case of a disease with no vaccine, mass infection is the only way to achieve herd immunity. But, while many could recover by developing antibodies naturally, allowing the disease to spread freely may cost us many lives and unwanted consequences.

“In recent times, Sweden opted to ease its lockdown measures to achieve herd immunity against COVID-19 [5]. However, it has resulted in a higher rate of infection and deaths in Sweden compared to neighboring Scandinavian countries such as Finland and Norway,” says Dr. Zeel.

  • If the herd immunity threshold drops in a community, then the disease starts to spread rapidly even before we realize it.

Vedix Tip:

Herd immunity through natural immunity is not a reliable solution for SARS-CoV-2 as the longevity of antibodies in an infected person is found to be not more than a few months. Until vaccines with proper efficacy are developed and distributed, you should not practice social distancing, continue wearing masks, washing hands, and other required practices.

The Last Word

Achieving herd immunity through vaccination is the safest way to protect yourself and others from getting affected by any infectious disease. While scientists are working relentlessly to develop vaccines, it is your responsibility to maintain healthy lifestyle routines and eat a wholesome diet which significantly contributes to immune response simulation. As per Ayurveda, maintaining the balance of tridoshas: Vata, Pitta, and Kapha is crucial in keeping your immune system healthy and ready to fight off against infectious diseases.

At Vedix, we customize Ayurvedic capsules for immune-boosting and gut health by analyzing your dosha levels and as per your unique body needs.

Know Your Dosha Now