Deltacron and XE show how coronavirus reinvents itself permanently

Viruses change all the time, often in ways that really hurt your chances of survival. But from time to time, those mutations can work in favor of the virus. The virus is unpredictable and has shown it in these pandemic years.

Many experts are wondering what the future of the coronavirus pandemic will be. Could there be a variant that will take us back to what we experienced in 2020? That is the big question that scientists are trying to answer.

“As the virus reproduces, there are errors when reproducing its code. Most of these errors result in a virus that is not competent or simply goes away,” said Dr. Mike Ryan, executive director of the Health Emergencies Program of the World Health Organization (WHO).

In March, the World Health Organization (WHO) verified the existence of a new variant that combines Delta and Ómicron and is called Deltacron. “We are aware of this recombination. It's a combination of Delta AY.4 and Ómicron BA.1. It has been detected in France, the Netherlands and Denmark, but at very low levels,” Dr. Maria Van Kerkhove, who's leading epidemiologist, reported at a press conference in Geneva. However, the expert clarified that for the time being, “no change in epidemiology or severity” was detected. “But there are many studies going on,” he said. In scientific literature, this new variant has already been dubbed 'deltacron', as stated in an article published in The British Medical Journal, although for now it is recognized as XD.

Apart from this new variant, the Director-General of the World Health Organization, Tedros Adhanom Ghebreyesus, expressed his concern that “several countries are drastically reducing diagnostic tests” for COVID-19.

“This inhibits our ability to see where the virus is, how it is spreading and evolving. Testing continues to be a vital tool in our fight against the pandemic, as part of a comprehensive strategy,” said the official. And in that regard, he warned that “many countries in Asia and the Pacific are facing an increase in cases and deaths from COVID-19.” “The virus continues to evolve, and we continue to face major obstacles in distributing vaccines, tests and treatments wherever they are needed,” he said.

According to Dr. Fernando González Candelas, from the Joint Infection and Public Health Unit of the Foundation for the Promotion of Health and Biomedical Research of the Valencian Community (Fisabio) and the University of Valencia, WHO only recognizes the recombinant variant XD as a variant under surveillance [VUM, Variant Under Monitoring]. “The XD variant is, in effect, a variant with part of Delta and part of Ómicron. Specifically, the protein S (spike) is of the Ómicron type (BA.1) and the rest of the genome corresponds to Delta,” said the expert.

He goes on to explain that there is “another recombinant variant, corresponding to the XE lineage, which has been detected in the United Kingdom and other countries and seems to be associated with a slightly higher transmissibility than the genomes that combine in it, both Ómicron, but one part is BA.1 and the other is BA.2. At the moment, WHO does not consider it a variant that needs surveillance, although it is for Public Health England because of the increased transmissibility detected in that country.” Experts call for calm and state that it is one more mechanism of the virus. “It shouldn't scare us. It has been happening throughout the pandemic and is going to continue to happen.

“This is the viral dynamic and the result of its ability to replicate, which it does so billions of times and helps the virus to change its genetic characteristic and find ways to survive in a hostile environment.” This is how the infectiologist and member of the Vaccine Commission of the Argentine Society of Infectology (Sadi) Francisco Nacinovich (75,823) began to explain to Infobae the reason for the emergence of the new subvariant. He continued: “Sometimes those changes make it (the virus) more efficient at continuing to multiply, spread and cause damage, and other times those changes, which make them randomly, allow only some of those characteristics. Maybe they make it very efficient to spread but with less impact on health, or the other way around.”

An official report published on March 29 by WHO says that the XE variant had been detected for the first time in the United Kingdom on January 19 by the United Kingdom's Health Security Agency. The study states that XE is 10% more transmissible than the BA.2 variant, which already had 75% infection power compared to the original Omicron, so in a few weeks it should become the predominant subvariant. Interestingly, and according to the US Center for Disease Control and Prevention (CDC), epidemiologists working for US health authorities are not monitoring XE, which has not yet been described as a 'variant of interest' or 'worrying variant'. However, WHO also specifies that monitoring of possible new mutations will continue as long as necessary.

Questions about how long or how often SARS-CoV-2 could follow its replication had already been raised with the emergence of the BA.2 subvariant, which, although it generated mild cases of the disease, its transmission rate caused outbreaks almost worldwide.

Experts in virology and genomics do not believe that recombinant XE is more severe or resistant to vaccines than other types of Omicron. Professor François Balloux, a geneticist at University College London, said the variant is likely to follow a path similar to that of the long-forgotten AY.4.2 Delta lineage, which aroused fears in Britain but failed to take off elsewhere. On his social networks, Professor Balloux said: “XE is not a worrying variant”.

The vaccines provided good protection against serious illness and death due to the previous variants, but experts highlight that a third dose of vaccine is known to be needed to provide the same level of protection against Omicron.

Birth of a subvariant

Experts warn that when the levels of transmission of the virus are high and there is a greater chance that a person will be infected at the same time with two variants. If this happens, the resulting variant “combines” genetic material from both “and if it succeeds and manages to be transmitted efficiently it becomes a new variant in circulation.

According to the United Nations health agency, today there is a global predominance of the Ómicron variant of the coronavirus. It is based on the consideration of the 382,789 sequences uploaded to the GISAID platform with specimens collected in the last 30 days. 99.7% were samples from patients with the Omicron variant. Only 0.1% were Delta, and 649 sequences were not assigned to a Pango lineage (0.2%).

“Keep in mind that the global distribution of coronavirus variants of concern should be interpreted taking into account surveillance limitations, including differences in sequencing capabilities and sampling strategies between countries, as well as delays in reporting. In addition, some countries may have changed their analysis and sequencing policies,” WHO commented in its weekly newsletter.

For González Candelas, in the current situation, given the different mutations present in the three main variants involved, delta and the omicron BA.1 and BA.2, “we continue to be more interested in whether the new combinations of mutations resulting from recombination had more important combined effects than separately, being able to increase transmissibility, decrease vaccine efficacy or result in failures in PCR diagnostics or render some monoclonal antibody-based treatments ineffective”.

At the moment of all recombinant XE variants it seems that it is the fastest growing, but it is not clear whether it is due to a local phenomenon in the United Kingdom or because of the variant itself. As of 5 April, 1125 cases of XE had been identified in the United Kingdom, up from 637 on 25 March. The first confirmed case has a specimen date of January 19 of this year, suggesting that it may have been in circulation in the population for several months. Since then, XE has been detected in Thailand, India and Israel. It is suspected that the latter Israeli cases may have developed independently. The United States has not yet reported any cases of XE.

Asked whether XE could cause a new wave of global infections, Nacinovich said that “of course it can produce outbreaks and here it is important to point out how science works.” “It is an example that, beyond any geographical, political or ideological border, science works collaboratively and in solidarity, and that is a very positive reality that invites us to think about how important it is to invest in science and education, which allows us to grow in all aspects and has implications in all scenarios of life. human”, he reflected.

“We are alert to this type of scenario that puts us with all the alarms ready to see what is happening in the country, and how this variant reaches Argentina,” Nacinovich concluded.

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