The evolution prospects of the SARS-CoV-2 variant that has won over all, but continues to mutate. What will the future changes of the virus look like? Will Covid always have the guise of Omicron or should we expect nasty surprises?
The SARS-CoV-2 Omicron variant turns two years old. a record because it is the most long-lasting (and fortunately the least lethal), but the questions that arise on this anniversary are: how long will it remain with us? Will its characteristics change? Will it be the definitive variant?
Omicron will dominate the other variants starting from November 2021 for an advantage in terms of ease of contagion. In terms of pathogenicity, it caused (in proportion to those infected) the hospitalization of a lower percentage of people. However, it infected (and still infects) so many people (even if vaccinated and already infected once) that it still caused several waves of hospital admissions. The US Centers for Disease Control and Prevention (CDC) monitored and reported that between October 2022 and September 2023, more than 80,000 people died from Covid in the USA, a number eight times higher than deaths from influenza.
Omicron is also changing over time: it has produced various sub-lineages that have disappeared or are still among us, we often remember them for the imaginative names that were given to them by the media, such as Kraken, Pirola, Eris.
A sublineage, XBB.1.5, the one on which the current updated anti-Covid vaccines are based.
In Italy, based on monitoring data updated as of November 20, EG.5 (or Eris, descendant from the sublineage on which the current booster vaccine is based) prevails with a proportion of 56.6%, followed by XBB.1.5 or Kraken (11.4%), XBB.1.9 (7.2%) and BA.2.86 or Pirola (equal to 6.6%).
Many specialists think that Omicron will be the definitive version of the SARS-CoV-2 virus and will be treated like the flu: a virus against which some categories of people should be vaccinated every year; other scientists are more cautious and warn that viruses have the ability to surprise us and Omicron itself continues to show extraordinary abilities to alter its surface, so much so that it increasingly evades the barrier of antibodies produced by vaccines or previous infections. What will happen then?
We asked Carlo Federico Perno, director of the Complex Microbiology Operational Unit at the Bambino Ges Children’s Hospital in Rome and Professor of Clinical Microbiology at Unicamillus University, to explain to us first of all why Omicron prevailed over the other variants.
There is only one reason why all viruses win over others: the ability to infect. What matters for a virus is to replicate. Whoever reproduces best wins and Omicron does it better than any other previous variant. Not because it causes “damage”, quite the opposite.
What awaits us in the future? Will Omicron always have the same characteristics (less lethal) than the first Wuhan virus?
What we can say is certain is different from what we can say is probable – underlines the expert -. it is certain that no virus has an interest in developing a more lethal variant, because viruses cannot live without us. Any virus tends to select a less lethal and more infectious strain: the opposite would go against all the rules of virology and Darwinism. therefore a more lethal strain is very unlikely.
Will there always be Omicron?
I think so: for the first time in a few months we have 3-4 Omicron sub-variants coexisting (Eris, Pirola and the others): it means that the virus is adapting and is no longer capable of developing a unique variant that is better than all the others. others – observes Perno -. The virus is reaching its optimum and for now a “shift”, i.e. a radical change, is not expected. We will continue to have what in virological terms we call “drift”, that is, the slow small steps of the virus towards further adjustments. Omicron is the result of an almost perfect adaptation of the virus to humans. That said, viruses do “what they want” and we cannot rule out the possibility of a “worse” variant emerging.
Researchers at the University of North Carolina have calculated that annual vaccination campaigns could save up to 49,000 lives a year in the US. What role does vaccination have now?
People get reinfected because the virus has changed itself exactly as happens every year with the flu: we are not protected from the infection that much – declares the specialist -. For a series of reasons, in fact, vaccines designed against Covid can protect well against serious disease, but protection against infection is modest. In vaccinated people, however, the course of the disease is usually benign: in the worst case scenario, a fever that lasts one or two days. It also works well as protection from previously becoming infected. Most of all, it works (and it has been well demonstrated) that those who have been vaccinated and have already caught Covid have a much greater set of immunity and protection than those who have only been vaccinated or those who have only had the disease. The elderly and immunocompromised people, however, are still weak in the face of Covid: we absolutely must protect the fragile, because they can still die from it.
Is it true that variants can arise within the bodies of immunocompromised people?
If an immunocompromised person has a modest immune system. What selects new variants is often the immune system, which, by blocking 99.9% of viruses, lets the 0.1% that “escape” from the defenses grow – says Perno -. In an immunocompromised person the immune system does not work and if it does not work it is difficult for it to select, therefore the probability that a new variant will be selected from a weakened person is quite low. The variants arise when the virus “wins” over people who have a good immune system: pushed to find “another path” and finds it. It is us healthy people who select new variations.
Will vaccines still need to be updated?
We necessarily have to adapt the vaccines, but when we are infected by Omicron it will always be a different variant from that contained in a vaccine (even an updated one). However, vaccines generate a “cross-reactive” immunity, that is, they can also protect against new variants. Getting vaccinated is always useful even if the vaccines are not exactly calibrated against the variant that is circulating at the given moment, concludes the expert.
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December 1, 2023 (changed December 1, 2023 | 10:31)
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