Bela Mondo

- WTF is Herd Immunity

Let us be topical. It is October 2020 and any adult living through this year is unlikely to forget it. A phrase has emerged that is now chucked around everywhere, discussed and argued endlessly by “experts” and non-experts. Here, we will take it apart and look at it at its simplest level. By doing this, we will get some clarity and understanding.

Herd Immunity

Go back about 300,000 years. Homo Sapiens (human beings) started appearing about then, though our predecessor Homo erectus (meaning ‘upright man’) has been in existence for around 2 million years. During all those years, our species obviously co-existed with many different organisms including bacteria, fungi and viruses. Some of these were beneficial and some were pathogenic to us. Humans adapted with our amazing biological defence mechanism (think about it, it really is incredibly amazing!). It pushed out the pathogens from our body systems to allow us to survive and reproduce till there are 7 billions of us now. Humans will not exist without the immune system, period.

In fact our modern vaccines only exist because of this immune capability. The vaccine is designed to stimulate and strengthen our existing immune response against a specific pathogen. Vaccines are pointless if we did not have this defence mechanism already in place.

So what happens if a very contagious pathogen hits us. We are at a disadvantage when compared to our ancestors. There are more of us now so we are more densely packed together and our ability to travel fast will cause illness to spread quicker. So the modern lifestyle of offices and cities and speedier transport systems exacerbates the speed of transmission of the disease.

Our immune system takes time to react and some of us will have a less effective response, usually due to pre-existing disease condition(s), or caused by the medication for it. That is why slowing down the spread of the pathogen can help reduce the severity of how it hits this group of people.

Coming back to herd immunity, what generally happens is the human defence system will react to the pathogen as each individual gets exposed to it. Our body’s immune response is triggered and will repel it and as more of us produce defensive cells, the pathogen runs out of hosts to inhabit and die out. That is what has been happening in the history of the human race.

So the term “herd immunity” is actually the naturally existing immunity in each of us individuals. It does exist and has been around for a few million years.

** Read Part II of this article **