From alpha to omicron: how the variants of the coronavirus prevailed or stayed by the way | Society

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Health personnel carry out tests with the new antigen test device in the WiZink Center pavilion in Madrid.
Health personnel carry out tests with the new antigen test device in the WiZink Center pavilion in Madrid.JPGandul (EFE)

From alpha to omicron, the SARS-CoV-2 coronavirus has traveled half the Greek alphabet in the form of variants suspected of causing more problems than those already proliferating. Not all have. Some remained mere threats. And, of all, the delta (and its lineage) has been the only one capable of imposing itself in practically the whole world thanks to its great contagion capacity. Nobody knows what will happen to the omicron, which now has the planet in tension. In a few months it could be forgotten, as happened to lambda (discovered in Peru) or mu (in Colombia); But it could also start replacing the delta and taking over its ecological niche. It is also not clear what the consequences of this would be: it is unknown if it produces a more serious disease or has more escape from vaccines.

The first time the majority of the population began to hear about variants of the coronavirus, it was still digesting the first waves. It was December 2020 and the World Health Organization (WHO) had not yet started using the Greek alphabet to name them. So it was known by the name of its origin, precisely what the WHO wanted to avoid in May 2021, when the delta began to proliferate.

The alpha variant, then known as British, arrived making almost as much noise as the omicron today. The UK Government sounded the alarm that the mutations they had detected were making the virus much more contagious and deadly. Most European countries, as has happened now, reacted by cutting flights with this country a week after London returned to confinement because of the variant. Spain took 24 hours longer to announce the measure than most of its neighbors, after a high-level meeting of the European Union in which they failed to establish a common position.

But, as is often the case with this virus, by the time those steps were taken it was too late. It is more than likely that the alpha variant was already circulating in Spain when flights were closed on the eve of Christmas, although the first cases were detected for the first time at the end of December. At that time, the country was already incubating the third wave, the deadliest to date, which spiked with the Christmas celebrations and reached its peak in late January.

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Most of the cases of that wave, however, were not caused by alpha, which was not in the majority until March, when it had already passed. The third wave was caused by a variant that at that time was not called by its original name, nor by any other outside the scientific field. For the public it was still simply “the coronavirus.” Otherwise, she would probably have been known as “Spanish.” According to Fernando González Candelas, professor of genetics at the University of Valencia and researcher at the Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (Fisabio), it was detected in the country after the great confinement of the spring of 2020 and it was expanding throughout half of Europe. Before that, the cause of the first wave was that of Wuhan, the original lineage.

“The substitution of some variants for others is given by their greater transmission capacity,” explains Candelas. This is combined with the level of infections where it spreads: if there are many, it costs more to replace it. If there are few, it is imposed more quickly. “This is what has happened in South Africa with the omicron, which has advanced very fast because there was little circulation. That is why we do not know if it is really more transmissible ”, he sums up. Its health authorities have reported this Wednesday that it has become the majority in the country in a month: in November, 74% of the sequences were of this variant, Reuters reports.

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The alpha itself was confirmed as more contagious than the previous one. And more than two other variants that were of great concern at the time and that were also labeled as of “concern” (VOC) by the WHO: beta (then known as South African) and gamma (Brazilian at that time). moment). Alpha, in fact, prevented these variants from prevailing wherever it was, which seemed to cause a more serious disease. According to the reading that is made, this variant, then so feared, could become an ally to stop other more dangerous ones. Because the evolution of the virus does not necessarily lead it to cause more damage, but to be more transmissible: it is Darwin’s theory seen almost in real time.

And the species Better adapted, so far, is clearly the delta variant and its lineages: it is no longer the same one that was discovered in India, where it caused a health disaster last spring. Although the first cases date from October 2020, it was not considered a variant of interest (VOI) until April 2021, a month before it was promoted to VOC on May 11. By then it was already expanding throughout the world.

In Spain it was detected for the first time on April 28 and became the majority in July. It is difficult to determine exactly when, since the sequences are slower than the virus, and their conclusions are usually a few weeks late. What is clear is that the fifth wave, which advanced faster than any other, was driven by the delta variant.

A different scene

But the scene had already changed radically. In Spain, the vast majority of the elderly and most vulnerable population were vaccinated. The virus circulated mainly among those under 40 years of age and was seven times less lethal than the previous ones.

The appearance of variants is something inevitable in viruses, as Federico Martinón, WHO’s advisor on vaccines, tells us: “They have emerged and will continue to emerge. At the moment, it mutates to the expected frequency and the omicron accumulates a number that falls within that rhythm ”. If the omicron has focused more attention, it is because the number of mutations and the type it has makes the uncertainty greater than others. Of the dozens of variants that have been identified by massive and connected sequencing around the world, only half a dozen came to be considered variants of concern. All, except the delta, have been losing ground where they began to prevail: beta in South Africa, gamma in Brazil or alpha, which is now practically extinct.

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No expert dares to predict what will happen to the omicron. “It may become predominant or it may disappear, we still don’t have enough data to evaluate it,” says Candelas. Its future will also depend on the extent to which vaccines are able to stop it. So far, they have proven highly effective in preventing the most serious illness and death, but they have been losing their ability to protect against infection with the newer variants. This is a probable scenario that the experts are considering now and that would make it easier for the omicron to take over the ecological niche that the delta occupies, although not necessarily be more serious.

It will take time to find out. First will come the in vitro studies that will show the immune response to the omicron of people vaccinated and those who are not. This provides some information on the contagion capacity, but not on whether punctures continue to protect in the same way from hospitalization and death. As Martinón explains, vaccines produce a “deeper” cellular immunity than that shown by the mere production of antibodies. Vaccines may need to be reformulated; what is clear is that those that exist already protect.

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George Holan

George Holan is chief editor at Plainsmen Post and has articles published in many notable publications in the last decade.

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