Tue. Jan 18th, 2022

As a tired world faces a third year of coronavirus, just as its spread is fueled by the most contagious variant to date, there is optimism among many scientists that the pandemic’s toll on world health in 2022 will ease.

Although Omicron threatens crisis over the next few months, the most likely scenarios show a much improved prospect thereafter due to increasing immunity among the world population, through vaccination and natural infection, which is likely to make the effects of the virus less severe.

“The upswing in Omicron cases in Europe and North America was extremely rapid and we could see an equally rapid upswing over the next month or two, although it could take four to six months for the variant to resonate around the world,” he said. said Jeremy Farrar, director of the Wellcome Medical Foundation.

“Then the immunity that has been built up will probably give us a period of calm, but there are a number of ways it can play out.”

Tim Colbourn, a professor at University College London, said it was “perfectly reasonable to think that Covid’s burden could be reduced by 95 per cent by 2022, so that it would no longer be a top 10 health problem. That would be a reasonable aim to end the pandemic. “

Some experts consider Omicron itself to be an indication of future evolution of the Sars-Cov-2 virus, as natural selection favors mutations that pass as quickly and efficiently as possible between people who already have some degree of immune protection.

Laboratory tests show that the mutations in Omicron made it much more contagious than previous variants in the nasal and upper respiratory tract – which favors rapid transmission – but conversely less likely to penetrate deep into the lungs where it tends to cause the most damage. to rig.

These conclusions are supported by epidemiological evidence that the risk of serious illness is reduced with half or more with Omicron.

Omicron’s high transmissibility means an astonishing 3 billion infections worldwide over the next two months, as much as in the first two years of the pandemic, according to modeling by the Institute for Health Metrics and Evaluation at the University of Washington.

“But this massive surge of infections and cases will lead to a smaller surge in hospitalizations than either the Delta Gulf or the peak last winter worldwide,” said Chris Murray, the institute’s director.

Evidence so far suggests that Omicron will displace Delta as the variant circulating in most parts of the world, just as Delta has wiped out previous tribes. “I am reassured by that prospect,” Farrar said.

“I would be more concerned if you had different variants circulating at the same time, because that would mean they exploit different ecological niches, and we would end up with a potentially dangerous dynamic of multiple strains interacting.”

People queuing for antigen tests in Portugal: whether new pathogens generally tend to milder over time as they settle into human populations is a matter of debate among scientists

Whether new pathogens generally tend to become milder as they settle into human populations is a matter of debate among scientists © Horacio Villalobos / Corbis / Getty Images

Even if Omicron does become the dominant strain, another variant of the virus is a certainty.

While individual changes to the genetic code are random events during viral replications – and no one made the provision multiplicity of mutations that characterize Omicron – the environmental pressures that allow some to thrive are predictable.

A world where most people are exposed to Sars-Cov-2 will prefer variants that transmit quickly and readily while evading the attention of the human immune system. Mutations that make the virus more lethal are unlikely to make it fitter and may even be a handicap if it impedes efficient transmission.

“Although you can imagine a deadly new variant emerging that is more transmissible, but also more harmful. . . I do not know how feasible it would be for this virus, “said Jennifer Rohn, a cell biologist and UCL professor. “Sars-Cov-2 is dependent on cell infestation and may already be close to the limits of its repertoire.”

Whether new pathogens generally tend to become milder over time as they settle into human populations is a matter of debate among scientists. But Paul Hunter, a professor of medicine at the University of East Anglia, is convinced that this is true of coronaviruses.

Four human coronaviruses, which have long circulated worldwide and caused mild to moderate cold-like symptoms, may have caused serious epidemics when they first moved from animals to humans.

In particular, the most recent arrival, OC43, crossed cattle in about 1889 and caused the pandemic then known as “Russian flu”, according to Hunter, which for four or five years caused increasingly mild waves of Covid-like disease – though not all convinced by the evidence.

“Sars-Cov-2 will continue to shed new varieties forever, but our cellular immunity will build up protection against serious diseases every time we become infected,” he said. “In the end, we will stop worrying about it.”

That reassuring scenario may apply if Sars-Cov-2 develops in a substantially linear manner. However, there is a small risk of a sudden evolutionary leap to “something from the left field that does not come from existing descendants,” Farrar pointed out.

One possibility is that Sars-Cov-2 develops in an animal population and then moves back into humans. Influenza pandemics usually start with a flu virus that is spread from birds or pigs.

Or Sars-Cov-2 can exchange genes with another virus through a “genetic recombination”. For example, if someone is infected simultaneously with Sars-Cov-2 and the related Mers coronavirus, which is not easily transmitted between people but kills about 40 percent of those infected, it is possible to suggest a nightmare hybrid that arises Which combined transmissibility and lethality.

Although such an evolutionary leap is not impossible, most experts consider it highly unlikely. “I’m much more afraid of another pandemic caused by a new virus we do not yet know about than of some variant of Sars-Cov-2,” Colbourn said.

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