Sunday, January 24

New mutations (300,000 have already been detected) are increasing infections by up to 50%



We are starting the third wave of Covid-19. It paints badly. We will once again see saturated hospitals, collapsed ICUs and doctors, without sufficient resources, forced to decide who has a chance to live and who does not. New restrictions and lockdowns are already beginning. Many more will come.

We knew that our Christmas excesses could cost tens of thousands of deaths. It is estimated that on these Christmas dates nearly 10,000 clandestine parties have been held with more than 100 attendees. Our irresponsible behavior and the incompetence of our authorities lead us headlong to catastrophe.

But not all fault is ours. So do the new mutant strains of SARS-CoV-2, which are significantly more effective at the time of infecting the ancestral strains from which they come.

Why?

With the Covid-19 pandemic there has been a unprecedented worldwide scientific effort, that among many other things has made it possible to sequence the new genetic variants of SARS-CoV-2 and relate them to their infectivity, their lethality and their possible resistance to the vaccine.

The results are impressive. Some 300,000 variants of SARS-CoV-2 have already been detected that differ by mutation from the original strain isolated in Wuhan.

Anyone who wants can enter the specialized portals that promote the rapid exchange of knowledge about the different genetic sequences of the coronavirus. For example, Nextstrain, O NCBI, O GISAID, O University of Luxembourg O o Covid19 Data Portal and consult where and when the new mutants appeared and what are their epidemiological and clinical effects.

What we can see there is not good news.

British or South African strains, extremely dangerous

Among the thousands of mutants that remain in coronavirus populations, a couple of strains have become famous and will soon be more so.

BRITISH STRAIN: At the beginning of December the new mutant strain known as B117 (also called VUI-202012/01). In no time it became dominant in the south-east of England. Later it expanded to the UK. He came to Spain (and the rest of Europe) with those who returned home for Christmas. It has already reached the west coast of the United States and even reached Australia.

He got it so fast because it is a much more infective strain than its predecessor.

SOUTH AFRICAN STRAIN: The same is happening in the other hemisphere. In this case it is the new mutant strain 501Y.V2 which was first detected in South Africa. This variant, which it is also significantly more infective that the ancestral strain from which it evolved, also has started its rapid expansion around the world.

They are potentially fatal strains because although They are not more lethal than their ancestors, as they have much more infectious capacity, they increase infections by around 50%. And more infections, more deaths and more hospital saturation.

At the end their great ability to infect makes them extremely dangerous.

This is not new. One of the SARS-CoV-2 strains that caused the most infections and deaths during the second wave was the G614 mutant that originated in Spain and it spread throughout Europe when the tourists who came in the summer returned to their countries. And that not many came.

But all of this, being bad, might not be the worst.

Too many mutations spike the risk

The new English strain B117 is characterized by something very unusual: it accumulates 23 mutations of which 17 are completely new.

Some of them affect spicule proteins causing them to more easily bind to recipient cells, thus increasing infectivity.

Others seem to get that increases the viral load in the upper respiratory tract and that each patient sends more viruses abroad.

That a virus accumulates so many mutations in such a short time is highly unlikely. Let’s see why.

Mutation is a rare event and SARS-CoV-2 does not have a very high mutation rate. Suppose that one virus in 10,000 suffered a mutation. The probability that a virus suffered 2 mutations is (1 / 10,000) x (1 / 10,000), that is, 1 in 100,000,000. The probability of accumulating 3 mutations would be 1 in 1,000,000,000,000 And so on.

In addition, most mutations have a deleterious effect (they are harmful to him) or they have no effect (they are neutral). Alone very few mutations are ‘beneficial’ and make the virus more infective.

As mutations occur randomly, these deleterious mutations should accumulate over time in the SARS-CoV-2 population, making the virus less effective.

So much so that It was even proposed to fight against Covid-19 with drugs that increase the mutation rates of SARS-CoV-2 to accumulate these harmful mutations (for him) as soon as possible.

Thus, the probability that a coronavirus strain that accumulates 17 new mutations is much more transmissible than the ancestral strain from which it is derived is very close to 0. Apparently it should never have happened.

But the fact is that new mutant strains of SARS-CoV-2 that are detected expanding in populations have significantly higher biological efficacy than the ancestral strains from which they are derived.

Of course, we could console ourselves by thinking that nobody gets the Christmas fat for 5 years in a row. Or if?

Largest evolutionary experiment in history

To understand the problem we must realize that we are witnessing the greatest evolution experiment in history. Never have so many scientists studied a virus so thoroughly and so quickly as SARS-CoV-2 is being done.

The key is that the population of SARS-CoV-2 is huge. Huge amounts of coronavirus are produced in the target cells of a single SARS-CoV-2 patient. Some conservative estimates calculate that a single patient releases at least 60 billion new coronaviruses.

Given the number of Covid-19 infected in the world, it is terrifying to think about the amount of coronavirus that is being produced.

Rarely have we faced a population of a virus (or any other organism) of such enormous size. And with the third wave there will still be more. So many of the things that did not seem possible become almost certain. Millions of new mutant viruses will appear in such a large population of SARS-CoV-2.

Amazing calculations

We can use precise mathematics to forecast the future. This study has recently been approached considering that the process of change in the frequencies of the different strains that appear by mutation in the SARS-CoV-2 population is a Markov process that can be characterized by diffusion equations, Kolmogorov equations or equations by Fokker-Planck.

And even if you don’t know how these things are calculated, the reality is that the results obtained are surprising.

And that almost all the new mutants that appear in the populations remain for a very short time before disappearing. And the time they last they will be in such low numbers that the vast majority of them will not even be detected.

Only those rare mutants that are much more infectious than the ancestral strain have a chance of becoming abundant in the population. And even then, most of them won’t have time to increase their frequency much. They do it slowly and Covid-19 has been around for a very short time.

But the extremely rare mutants that are at least 50% more infective than the ancestral strains from which they come, in just 3 to 4 months they can become dominant in the population.

They do it in a sequential way. They first increase their numbers thanks to a few favorable mutations. The more viruses there are, the more likely they are that new mutations will appear that make them even more infectious.

Here is the key. I’m never going to get 5 years in a row for Christmas fat if I only play a few numbers. But if luckily I get the first year and then I spend all that money on tickets for the next year, I greatly increase the probability that I will touch again. In the limit, if I always buy all the numbers, it is sure that it always touches me.

By allowing such a high number of people infected with Covid-19, we are giving SARS-CoV-2 the opportunity to win the lottery. As long as the coronavirus population is so large, millions and millions of new mutant viruses will appear. We are giving it a try so that mutations appear that make them much more contagious.

Let’s not forget that we are playing against the coronavirus in a world similar to the one described by mathematician Lewis Carroll in 1871 in his book “Through the Looking Glass and What Alice Found There.” The Red Queen tells Alicia: “In this country to stay where you are you have to run as fast as you can. If you want to go somewhere else, you must run at least twice as fast.

Regarding the moment in which the Covid-19 pandemic broke out, we improved a lot in prevention, we used a mask, we improved medical treatments, etc., but we remain tied because the coronavirus also improves, becoming more and more infectious.

We can’t stop improving or the virus will win.

We can win this battle but …

Being pessimistic the emergence of these new mutants pose bleak scenarios. SARS-CoV-2 seems adept at jumping the species barrier. Mutants could appear that infect other animals that end up becoming the reservoir of the disease. It’s even possible though unlikely, that new mutant strains will appear against which the vaccine is not very effective.

We can win the battle. We are close to it. We have the vaccine. Now is when we must try harder. Let’s try to make the third wave as small as possible.

For few people to be infected we must remember that An excellent work on contact tracing to identify infectious foci was recently published in Nature (the best scientific journal in the world) that cause Covid infections.

It’s about a detailed study of 98 million people through their mobile phones. Their movements were monitored to see where they got infected. It is the most robust tracking work carried out to date (although it has small limitations since children, inmates or the poorest do not usually have mobile phones).

Its conclusions are very clear.

– The vast majority of people got the coronavirus in a bar, a nightclub, at a restaurant table, or at a clandestine party. Bad news for us that we are the country in the world with the most bars and restaurants per inhabitant and the one that spends the highest percentage of its salary in hospitality.

Next comes a surprising place: Gyms and sports centers. Depending on where it is done, exercising is not always healthy.

Finally, the meeting places associated with culture follow: classrooms, cinemas, theaters, and even some places of religious worship.

Let’s think that if many people get infected we will give SARS-CoV-2 a chance to win.

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