How does the pandemic end: what comes after Omicron?

As a tired world faces a third year of coronavirus, as well as its spread left by the most contagious variant to date, there is optimism among many scientists that the burden of the pandemic on global health will decrease in 2022.

Although Omicron threatens a crisis over the next few months, the most likely scenarios show a much improved outlook then due to rising immunity among the global population through vaccination and natural infection, which is likely to make the consequences of the virus less severe.

“The recovery in Omicron cases in Europe and North America has been extremely rapid, and we can see an equally rapid decline over the next month or two, although it may take four to six months for the variant to resonate around the world. , “said Jeremy Farrar, director of Wellcome’s medical fund.

“Then the immunity that has been built up will probably give us a period of calm, but there are a number of ways in which this could unfold.”

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

Some experts see the Omicron itself as a pointer to the future development 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 immune protection.

Laboratory tests show that the mutations in Omicron have 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 do the most damage.

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

Omicron’s high transmissibility means a staggering 3 billion infections globally over the next two months, as many as in the first two years of the pandemic, according to modeling from the Institute for Health Metrics and Evaluation at the University of Washington.

“But this massive increase in infections and cases will result in a smaller increase in hospitalizations than either the Delta wave or the peak last winter globally,” said Chris Murray, the department’s director.

So far, evidence suggests that Omicron will displace Delta as the variant circulating in most parts of the world, just as Delta swept past tribes away. “I’m reassured by that view,” Farrar said.

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

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

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

Although Omicron will be the dominant strain, another variant of the virus is a security.

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

A world where most people have been exposed to Sars-Cov-2 will favor variants that are transmitted quickly and easily while evading attention from the human immune system. Mutations that make the virus more deadly will hardly make it better and may even be a handicap if they prevent efficient transmission.

“Although you can imagine a deadly new variant 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 depends on infecting cells, and it may already be close to the limits of its repertoire. “

Whether new pathogens in general tend to become milder over time as they become established in 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 for coronavirus.

Four human coronaviruses, which have long circulated around the world 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 over from cattle around 1889, causing the pandemic then called “Russian flu,” Hunter believes, causing increasingly mild waves of Covid-like disease for four or five years – though not everyone is convinced of the proof.

“Sars-Cov-2 will continue to throw up new variants forever, but our cellular immunity will build protection against serious illness every time we get infected,” he said. “Ultimately, we stop worrying about it.”

The 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 out of the left field that does not come from existing genera,” Farrar pointed out.

One possibility is that Sars-Cov-2 develops in an animal population and then moves back to humans. Influenza pandemics usually begin with an influenza virus that jumps from birds or pigs.

Or Sars-Cov-2 could exchange genes with another virus through a “genetic recombination”. For example, if someone was infected at the same time as Sars-Cov-2 and the related Mers coronavirus, which is not easily transmitted between humans but kills about 40 percent of those infected, it is possible to imagine a nightmare hybrid that combined transmissibility and mortality.

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

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