Herd Immunity Against Coronavirus: What Is It And Can It Help India Beat COVID-19?

Since the outbreak of Coronavirus across the world, countries have been targeting to achieve herd immunity against it as the only guarantee of normalcy to return.

The idea is simple, once herd immunity is reached, the virus will not have too many ways to spread to those not immune to it.

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For herd immunity, around 70% to 90% of the population of a region should be immune to the virus. When this happens, it would give an indirect immunity to those not immune to it, simply because no infected carriers will be available for the virus to spread through.

How herd immunity works

There are two ways of achieving immunity at this scale and at a pace this fast. One, and usually the safer way, is to administer vaccines against diseases to the masses. Measles, mumps, polio, and chickenpox are examples of infectious diseases for which vaccines were used to establish herd immunity.

The other way is widespread infections, based on the assumption that majority of the population will be able to develop immunity against the disease. As can be understood, this is a risky strategy and still leaves certain age groups vulnerable to the disease, as herd immunity is mostly focussed on the healthy, young portion of the population.

A number of experts have been advocating the latter to develop herd immunity against the novel Coronavirus. Countries like UK even practiced it during the initial stages. UK Prime Minister Boris Johnson supported it back in March and hence did not ban large gatherings or close schools.

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The plan evidently failed, though. Johnson issued a nationwide stay-at-home order later in March. Since then, the number of infected in the UK is nearing 150K, with total deaths having crossed 20,000. Johnson later contracted the virus himself. But why is herd immunity so difficult to achieve with the latter approach?

There are multiple reasons for it.

One reason is that even if the infection is allowed to spread among young, healthy people, the virus might be enough to hospitalise, if not kill them. At the rate of community transmission, that would prove to be a burden on the medical resources in a country.

Overwhelming of hospitals and other resources might then lead to an increase in deaths due to other infections, or lack of medical resources too.

In another undesired scenario, the disease can also spread from one generation to another, considering multiple generations of a family live together in a country like India.

That is also why lockdowns are being observed across the globe. To control this rate of spread, stretch out the number of cases observed within a day and hence avoid a burden on the medical supplies. Another and a deeper rooted issue with the COVID-19 is that the development of immunity in a host against the virus has not yet been proven.

(Representative Image: Reuters)

Dr. Maria Van Kerkhove, an infectious disease epidemiologist at the World Health Organization (WHO), explained as per a CNN report that it's not known whether people who have been exposed to the virus become completely immune to it and if they do, for how long is it effective. That's why governments should wait for a vaccine, she said.

The third reason raises questions on the on-ground practicality of the concept. Even if a portion of the population is allowed to resume work and get infected with the virus, and even if they develop the immunity against it, the number of people getting infected just might not be enough to develop herd immunity.

So why is herd immunity being advocated?

Gaining herd immunity through widespread infection would render the ongoing lockdown strategy useless. Instead, the masses will be allowed to engage in outdoor activities, as is being observed in Sweden.

This would mean that the economy would not be as affected by the Coronavirus outbreak as is the norm being seen across the globe.

On an optimistic note, the strategy can be used to bring down the mortality rate of the virus. This is again based on the assumption that the young generation of a region will be able to host the virus without being hospitalised or dead. This would in turn protect those in their old-age or the newborns.

It can, however, be understood that the risk carried by the radical concept is too high. So if herd immunity is to be achieved, a tested and proven vaccines for the COVID-19 will be a much better way to do so.