Why won't Ómicron be the last shock of the covid?



Every time a virus copies itself, there is a chance that the replication will include some error. There is also a possibility that some of these errors will turn into a stable change in the virus genome. Some of these stable changes, coincidentally, will represent an evolutionary advantage and will allow the virus to improve its transmission capacity, or to be more serious in its effects on health. It may even be that some of these accidental errors or the combination of several allow a change relevant enough to modify the so-called "spike protein", or spicule, precisely the protrusions of the virus that serve to adhere to cell receptors. This protein is the key that the virus uses to unlock a lock (the ACE2 receptor) in our cells. Precisely vaccines against coronavirus are based on "teaching" our body to detect that key of the covid in advance and prevent it from entering the cells causing contagion. But if the virus, because of that long chain of random mutations, finds a different key that allows it to inoculate its genetic code into our cells, the effectiveness of the vaccines will be diminished. That is roughly the reason why the world's disease control centers jump warnings every time it is detected that a virus mutation begins to be successful in being transmitted. What it does not explain is the reasons why different countries react more or less drastically.

The Omicron variant of the covid has unleashed concern in Europe, and adds to the wave of infections that has returned to occur at the gates of Christmas. But what do we know for sure about her? What are the uncertainties that motivate the alarms? And because Omicron will not be, with great certainty, the last shock?

Mutation, lineage, variant

Each word has a different meaning. A virus mutation is a single change in the genome. They happen very frequently, but only sometimes does this change mean that the virus modifies some of its characteristics. Viruses that have multiple mutations and have a common ancestor constitute a lineage. With all these alterations, it happens that some genetic codes of the virus, with one or more mutations, begin to arouse concern and acquire relevance to be considered variants of the virus. The health authorities classify these variants according to their possible incidence in the public health.

Where does the name come from?

Initially the variants were named according to the place where they were detected (they will remember the “Indian variant”, the “South African” or the “Brazilian”), but in May 2021 the WHO decided to use the Greek alphabet to designate them and thus not stigmatize no country. In this way, the different letters were used in order, but it was decided to skip two of them: Nu and Xi. The reason is that Nu had a certain phonetic similarity with “new” (new in English) and that Xi is a very common surname in China. Following the good practice manuals, which recommend avoiding naming diseases with names that may be offensive to any group, the International Committee on Taxonomy of Viruses went directly to the letter Ómicron. Actually, the scientific way to refer to this variant is B.1.1.529, a designation that allows the lineage of this new aspect of the virus to be traced.

Observe, care, care

The health authorities classify each variant according to the degree of concern it arouses. If only they should be taken into account, because they do not vary in a special way the ability of the virus to be harmful, they are considered "variants under monitoring". In the United States, this category includes Alpha, Beta, Gamma, Epsilon, Eta, Iota, Kappa, Mu, Lambda, and Zeta. Of most of them, except for the first three, we have hardly heard as much as “Ómicron”, but some were temporarily considered “variants of interest”, until its true impact could be evaluated. The "variants of interest" are those that arouse attention, that offer indications that they may be more transmissible and that, therefore, require a higher level of attention. Currently in Europe the Mu and Lambda still remain as “variants of interest”. The next step is that of "variants of concern." They are those for which there are already indications of greater transmissibility and their genetic modifications suggest that it will have an impact on public health. The United States only maintains as "variants of concern" the Delta and Omicron. In the EUInstead, the Beta (South African) and Gamma (Brazilian) variants are also considered.

Where did Ómicron come from?

It is one of the unknowns. Their genetic modifications appear to come from pre-Delta variants, so there must have been an undetected lineage fork. There are several suspicions: that the virus has circulated among people outside the Delta variant, that it was generated in a chronic patient adding mutation after mutation, or that it has been present in animals until it returns to humans again.

What are the certainties about Omicron?

The first detection of this variant of the virus occurred in Botswana, on November 9, 2021, by the Network for Genomic Surveillance in South Africa. It was found that there was an increase in infections in the areas where it was detected, but with low rates of vaccination. This variant was soon found to include worrisome mutations. It incorporates a large number of them (more than fifty), of which thirty refer to the spicule of the virus. Given that the spicule is the key that the virus uses to enter cells, so many alterations can have consequences in the transmissibility of the virus, its ability to evade the immune system and resistance to hitherto existing vaccines. It will still take a few days before the scientific community can be certain, but the warning issued has already been enough to unleash concern in some countries that have rushed to prevent movements to the southern African cone, despite the fact that they already have contagions on its borders. The latest data seem to consider that the Omicron variant has a greater capacity to reinfect people who have overcome the disease. But there is still no certainty that the symptoms are more severe. The European Center for Disease Prevention (ECDC) has only pointed to uncertainties, but it has been enough to put countries on their guard.

And why do the alarms go off?

The ECDC notice (dated December 2) specifically specifies that "the evidence from the initial cases is limited", but "suggests" that the Omicron variant may be associated with greater transmissibility than the Delta variant, "although there is still a need for it. more robust evidence ”. It further says that there are "considerable uncertainties" regarding the effectiveness of the vaccine, the risk of reinfection and other properties. Under these conditions, set the probability that the variant will be installed in Europe as “high”. It also indicates that the severity of disease in Omicron variant virus infections remains "highly uncertain" and that there are serious concerns about whether it could significantly reduce the effectiveness of the vaccine. Given that the effects of the Delta variant are still faced in many European countries, the ECDC indicates that the impact of an Omicron spread could be “very high”. Therefore, "based on the information currently available and considering the high level of uncertainty, the total risk for European countries is set at high or very high", concludes the ECDC. Of course, it is noted that for now there are no serious cases or deaths detected by Ómicron. That is to say, it is the unknowns that put on guard, not the evidence.

When can we have more clarity?

Scientists estimate that there may be more certainties within two weeks. Uncertainty is an invitation not to raise our guard, to continue to maintain protection guidelines and to be cautious. But countries, especially those hit by the latest wave, have been quick to put up firewalls. There are optimistic signs: Vaccine manufacturers have pointed out that if Ómicron could overcome the barriers of current immunization, they could alter future doses to combat it. It is also believed that the type of mutations should not affect treatments in the experimental phase and that they aim to reduce hospitalizations and deaths.

Why are we exposed to so many more future variants?

Remember that virus mutations are random and happen, it is true that in a very small percentage, each time it replicates. But a single virus that infects a human can make on the order of 100,000 copies. An article published last June in the academic journal PNAS estimated that in each patient infected with covid, at the peak of the disease, there may be between 1,000 and 100,000 million viruses. And it is estimated that approximately one mutation occurs every 200,000 infections and that one of them settles in the world every day. The sum of mutations in each lineage would be three per month, with which there is a certain risk that new variants will appear. And that risk increases if the circulation of the virus continues to be high, with a high number of infections. The vaccine is effective, but the percentage of vaccinated people is very low in less developed countries. Hence, the WHO warns of the importance of extending this campaign and recalls that the battle against the virus is global; No country can be taken for granted, even if it has a high vaccination, as long as there are territories in which new variants can be generated that, in the end, will eventually reach any other corner of the planet.

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