Everything About Herd Immunity Simplified So That a 5-Year-Old Can Understand


Last Updated on 2020-04-10 , 10:59 pm

Since the coronavirus started spreading all over the world, two words have repeatedly been uttered because of its significance for the future of mankind:

Toilet paper.

Uh no, not that.

Herd immunity. 

Yes, that’s the one.

But just like what reporters must have been thinking when Donald Trump said he knew the Covid-19 outbreak was a pandemic before anyone else knew it was a pandemic, what the hell does that mean?

Well, that’s why I’m here, dear reader. Here’s everything you need to know about herd immunity in language even a chimpanzee can understand.

Everything About Herd Immunity 

Very simply put, herd immunity is when a large group of people is immune to a disease, which makes it hard for the disease to spread further.

If I were to put it in even simpler terms, you got a herd:

Image: YouTube

You got an immunity:

Image: YouTube

Ahh, herd immunity:

Image: YouTube

Reader: That was completely unnecessary

You may be right. Anyway, herd immunity works like this: imagine you have a large group of people, like a herd of sheep.

If most of the individuals are immune to the disease, then an individual in the middle of this group is unlikely to become infected, because the virus has a very hard time getting through the herd.

Image: YouTube

Herd immunity, then, happens when people in a community are protected from a virus to a degree that people who are not immune are still protected because of the high population immunity.


But to really understand this phenomenon, you first need to know what it means to be immune to a disease.


Humans can achieve immunity to a disease in two different ways: vaccine or immunity developed through previous infection.

You see, every time a virus or bacterium invades our beautiful bodies, our immune system has to fight it off.

In the bodies of those who are strong enough, the immune system creates antibodies and immune cells that inactivate or destroy the specific infectious organism.

And if we encounter the same organism in the future, the immune system “remembers” that previous exposure and can mount a defense.

Image: YouTube (TED-ed)

But not everyone is strong enough to fight off diseases, of course, that’s why we have vaccines.

Vaccines are designed to prevent disease, rather than treat a disease once you have caught it.

A vaccine contains a weakened or killed form of the virus that causes the disease so your immune system can easily fight it off and create antibodies, making you immune to the virus in the future.

The only problem is that it takes a long, long time to develop a vaccine; even though scientists are racing to get one ready, it will take at least 18 months until we have one for Covid-19.

Image: Giphy

So, what can we do in the meantime? Let many people get it and fight it off so we can eventually develop herd immunity, right?

Reader: Yes, that sounds about rig-



Reader: Ok ok please stop shouting

You see, the UK tried that for Covid-19, and it didn’t work out too well.

Why Achieving Herd Immunity Naturally is Bad

Unlike many countries who imposed lockdowns and social distancing measures, UK’s initial strategy was to let everyone, except the elderly, contract the disease so the whole population would eventually get herd immunity.

But there’s a problem with this strategy. When experts talk about herd immunity, they’re actually referring to vaccines.


“You don’t rely on the very deadly infectious agent to create an immune population,” says virologist Akiko Iwasaki at the Yale School of Medicine to the Atlantic.

Why? Because it’ll lead to a high rate of infections and deaths.

Ultimately, the reason why a natural herd immunity strategy won’t work is that it’ll end up overwhelming healthcare systems.

And when that happens, there won’t be enough beds and ventilators for everyone, which means that more people will die.

Take the UK for example. Though they have since switched gears, if the UK had continued with their herd immunity strategy, experts calculated that over 47 million people would need to be infected and then recover to achieve herd immunity.

This estimate is based on the idea that 70% of the population needs immunity to prevent the Covid-19 virus from spreading.

But if this happens, then over one million people will die and eight million will need critical care.

Image: Giphy

Moreover, this strategy makes the dangerous assumption that young people won’t die from the disease, which is not true. I’m sure you’ve heard of the 6-week old newborn who recently died from the illness and many young adults who have developed serious complications after contracting the virus.


This is why the UK changed its strategy and implemented social distancing measures instead.

Even if we could magically infect 70% of the population with only a few deaths, it is not always possible to achieve herd immunity for very long. Some viruses, such as seasonal flu, mutate frequently, evading the body’s immune response.

Vaccines are the only way

This means that the safest way to achieve herd immunity against Covid-19 isn’t naturally over time, but through a vaccine. Mass vaccinations in the past have been highly successful in inducing herd immunity for many diseases like measles, mumps, and rubella.

As The Hill put it, “herd immunity is not a strategy for responding to an ongoing outbreak. Herd immunity is the reason why vaccines are effective in preventing outbreaks.”

So, what do we do in the meantime? Well, you’re probably sick of hearing the phrase, but-

Reader: Don’t say it

But it’s the only way to combat the pandemic right now.

Reader: If I hear the phrase social distancing one more time…

Uh… so… social distancing is-

Reader: *collapses*

Social distancing is especially important for a disease like Covid-19 because it’s highly contagious and often presents very mild symptoms.

This means that people can transmit the disease without even knowing it.

So, until we have a vaccine readily available, stay at home as much as you can, keep a distance from others when you’re out, and see a doctor if you’re unwell.

Herd immunity against Covid-19 may be achieved in the future, but for now, it’s a distant dream.