Amsterdam, 24 July 2021

As many of you will know, I studied biology and spent nearly twenty years teaching the subject at secondary school in the Dutch town of Wageningen.
I notice that many people around me do not have the slightest idea how variants or mutations of viruses develop – for instance the Delta variant of the coronavirus, which is more infectious than what we had before, so that some of the lockdown relaxations in the Netherlands have had to be reversed.
I will explain it without using difficult words.

A virus is a tiny germ consisting of a core of hereditary material coated with protein. If such a virus lands on the damp, soft inside of your nose, mouth or throat, or in the area round your eyes, it first of all settles there comfortably. But soon it tries to reproduce.

A virus has the incredible ability to turn our bodies into a kind of factory that makes very exact copies of it. Of course it needs components to make the copies, both for its core of hereditary material and for its protein coat. The components come from our bodies, so the virus gets them for free. And that’s when we start to get ill.

But just being slightly ill isn’t enough for the virus. The new copies go deeper into our bodies. There are plenty of little blood vessels in the soft, damp places where they start out. And once they have penetrated such a little blood vessel, they let the blood carry them to other organs – where our bodies again start making copies of them. There are soon millions of copies, which together try their best to make us even more ill.

But, strangely enough, our bodies do something very different at the same time: they try to make as many of the copies harmless as they can and clean them up. And it is these bodily defences that you are supporting strongly when you get yourself vaccinated.

But how do variants or mutations develop? This happens while the copies are being made. Of course the copies should be completely identical to the original virus. Most of the time they are – but every now and then a mistake is made, and we get a single virus that is very slightly different from the original one.

The mistake is nearly always harmful to the variant or mutation, and then our defences get rid of it without anyone noticing a thing. But very occasionally the mistake helps the newly-made virus – for instance by allowing it to penetrate new organs, or overcome our defences, more easily. So the mutation survives, and our bodies begin to make copies of it, all of them with the same advantage. Because they are more effective than the old copies they will replace them, and soon the person will be full of the mutated copies. And if the person infects other people, they will be infected with the new mutation.

Overall the chance that a new variant or mutation will develop is thus very small – but the more copies are made the greater the chance, for it is while copying that the mistakes are made. The more copies, the more likely mistakes will be made and the more likely that such a mistake is in favor of that one newly made copy, the new variant.
The chance that such a new variant will subsequently have the opportunity to infect large numbers of new people is of course greatest in areas where large groups of people who are susceptible to the virus are still walking around. And those are exactly the areas where few people have been vaccinated, so not just here in the Netherlands or Europe, but also in the many densely populated areas in other parts of the world, far away from here. The more chances the new variant gets to infect new people, the more copies will be made, and the more mistakes that will help the new virus become even more effective. And so on, and so on.
So it is no wonder that most of the variants that have developed so far and have come to harass us here in the Netherlands and Europe – Alpha, Beta, Gamma, Delta, etc. – have originated in such areas.