5 keys to the XE subvariant: could it cause a new wave of COVID-19 infections globally?

With fewer and fewer restrictions on movement around the world, and as countries try to resume the pace of life prior to the COVID-19 pandemic, SARS-CoV-2 and its evolution - and expected - viral dynamics are once again surprising with a new variant that triggers alarms.

Detected at the end of March in the United Kingdom, the new variant is already present in other European countries, India, and Brazil announced the first infection attributed to the brand-new mutation yesterday.

In its epidemiological update report of 29 March, the World Health Organization (WHO) described it as a result of the combination between the original Ómicron variant (BA.1) and the sublineage BA.2, also known as Silent Ómicron. And he named it XE.

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.

And although for the time being the first reports describe it as silent, highly contagious and with still unclear symptoms, the truth is that XE would be transmitted 10% faster than its predecessors and its speed of spread is still under study.

Viruses, as in any organism, occur random mutations, that is, alterations of genetic material. Most of these mutations will have no effect, but others can modify the characteristics of the virus, they can even give it advantages. For example, some of the mutations of the coronavirus have facilitated its entry into human cells, making it more contagious.

“In the history of man there have been at least six or seven jumps of coronavirus species from animal to man so far and SARS-CoV-2 is just the last. In all other cases, what happened was that after an acute phase, the virus became much milder,” said Professor Mario Clerici, professor of Immunology at Milan State University and scientific director of the Don Gnocchi Foundation, on the occasion of the outbreak that BA.2 caused in Europe. And he expanded: “And all these coronaviruses, except MERS which, however, is another story, have always lived with us and give us symptoms that are very mild, very mild colds. So if we are based on what happened with all the other coronaviruses, it is quite logical to assume, to expect, that the same thing will happen with this one as well.”

1. Is it a more contagious variant?

The WHO classified the XE variant as a “high concern” because it arises from the combination of two highly contagious strains, such as Ómicron (BA.1) and Silent Ómicron (BA.2). 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. However, research is still active to determine whether it is the most contagious variant. At the moment, it remains within the range of what was already known about the Ómicron variant.

The agency also acknowledged that the study of the spread of COVID has been complicated in recent weeks due to fewer diagnostic tests being carried out. This means that data is “less significant” and “less robust” and, therefore, more difficult to trace “where the virus is, how it spreads and how it evolves”, with research being key to estimating the possibility of entering a new phase of the pandemic.

2. Does it cause the same symptoms?

The first estimates of the WHO study do not indicate that the new variant has symptoms different from those generated by the already known strains of SARS-CoV-2, nor that the conditions it causes are more severe.

Hence, specialists agree that the way the infection manifests itself in the body will continue to be with fever, fatigue, runny nose, sore throat and headache.

However, in its latest report, the agency highlighted that it “continues to closely monitor and assess the public health risk associated with recombinant variants, along with other SARS-CoV-2, and will provide updates as more evidence becomes available.”

3. Do existing vaccines protect?

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.

4. What is the difference between a variant and a subvariant?

Dr. Angela Rasmussen, a virologist at the University of Saskatchewan, in Canada, said that “there is no reason to be nervous”. He noted that XE is one of the many recombinants of Ómicron BA.1 and BA.2. “As such, as much as it succeeds, it will still be a sublineage of Ómicron.” Delta had more than 200 sublinages of this type before being displaced by Ómicron.

He also noted that “XE is not a Greek letter that designates a new variant of interest. It's just a recombination of Ómicron, the fifth identified, after XA, XB, XC and XD.” He advised that the same precautions should be taken for COVID-19 in general.

Meanwhile, Professor Susan Hopkins, chief medical adviser at the British health agency UKHSA, stated: “Recombinant variants are not unusual, especially when there are several variants in circulation, and several have been identified during the course of the pandemic to date. As with other types of variants, most go extinct relatively quickly. This particular recombinant, XE, has shown a variable growth rate and we cannot yet confirm whether it has a real growth advantage.”

5. “Mixed” variants are common

As viruses mutate over time, recombinant variants are likely to be produced.

“It's happened a few times, and usually the way it happens is that when two variants circulate and someone gets infected with both at the same time, then the virus recombines with the characteristics of both variants.” Carlos Malvestutto is MD, an infectious disease specialist at the Wexner Medical Center at Ohio State University, and in a recent interview he confirmed that, so far, there is no indication that the XE variant is better at escaping immunity obtained by a previous infection or vaccination.

“We don't really see in these few cases that have been seen in the UK, China and India that it is causing a serious illness,” he said.

What are the experts saying

“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.”

According to the infectiologist Roberto Debbag (MN 60253), “the data that is known about circulation in some European countries is that it is a variant of recombination, that is, when the incidence of infection increases due to increased circulation, it also affects immunocompromised hosts and they occur recombinations”.

And after assuring that “today the degree of contagiousness and the impact it will have is not known, nor is it circumventing the immune system”, the specialist said that “it is expected that it will possibly be very similar to Ómicron”.

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 these types of scenarios that put us with all the alarms ready to see what happens in the country, and how this variant reaches Argentina,” said Nacinovich, as for Debbag, “that this subvariant produces an impact will depend on each country because it is known that there are four variables that make it possible to have what is called a ping pong effect, that is to say epidemic outbreaks of COVID in different parts of the world”.

And in that sense, he enumerated: “the rate of population vaccinated, the types of vaccines used, the vaccination strategies in childhood and whether the impact of Ómicron in recent months generated immunity in the community.”

On that, Nacinovich concluded: “This new context posed by the XE subvariant is also an incentive for people to agree to complete vaccination schedules, which is very important especially now that the flu is circulating and the pictures can be confused.”

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