An electron microscope picture reveals a SARS-CoV-2 particle remoted within the early days of the pandemic. It’s been practically a 12 months since omicron was first detected, and scientists say this department of the coronavirus household tree continues to be thriving.
NIAID/NIH by way of AP
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NIAID/NIH by way of AP
An electron microscope picture reveals a SARS-CoV-2 particle remoted within the early days of the pandemic. It’s been practically a 12 months since omicron was first detected, and scientists say this department of the coronavirus household tree continues to be thriving.
NIAID/NIH by way of AP
Throughout the pandemic, the virus that causes COVID-19 has been evolving quick, blindsiding the world with one variant after one other.
But the World Health Organization hasn’t given a SARS-CoV-2 variant a Greek identify in nearly a 12 months, a transfer that is reserved for brand spanking new variants that do or might have vital public well being impacts, akin to being extra transmissible or inflicting extra extreme illness.
That raises the query: Has the evolution of the virus lastly began to ebb, probably making it extra predictable?
The reply — in response to a dozen evolutionary biologists, virologists and immunologists interviewed by NPR — is not any.
“SARS-CoV-2 is constant to evolve extraordinarily quickly,” says Trevor Bedford, a computational biologist who research the evolution of viruses on the Fred Hutchinson Cancer Center in Seattle. “There’s no proof that the evolution is slowing down.”
Instead, essentially the most consequential evolutionary adjustments have stayed confined to the omicron household, relatively than showing in solely new variants.
Whereas alpha, beta, gamma and the opposite named variants sprouted new branches on the SARS-CoV-2 household tree, these limbs have been dwarfed by the omicron bough, which is now studded with a plethora of subvariant stems.
“The kids of omicron — so the numerous direct kids and cousins inside the various omicron household — these have displaced one another” because the dominant strains driving the pandemic, says Emma Hodcroft, a molecular epidemiologist on the University of Bern. “But that very same household has been dominating” by outcompeting different strains.
One variant to rule all of them
The ever-expanding omicron brood has maintained its dominance via what’s often known as “convergent” evolution — when entities independently develop comparable traits due to comparable environmental pressures, in response to Manon Ragonnet-Cronin, who research viral genetics on the University of Chicago.
“We appear to be seeing for the primary time proof of widescale convergent evolution,” Ragonnet-Cronin says. “We have what persons are calling a swarm of omicron viruses, which have completely different ancestries inside omicron, however which have the identical set of mutations.”
Those mutations endow these omicron offspring with the one energy they want most proper now: the flexibility to sneak previous the immunity that individuals have constructed up from getting contaminated, vaccinated, or each.
“When you see convergence in evolution that is evolution’s approach of claiming ‘this mutation is repeatedly getting chosen time and again as a result of it is actually useful,'” says Jesse Bloom, a computational biologist on the Fred Hutchinson Cancer Center in Seattle.
Those mutations within the virus’s spike protein have been rising its capability to evade protecting antibodies and proceed infecting huge numbers of individuals.
“This virus is getting a number of lottery tickets if you’ll. And it appears to be like like, with these new variants, these new mutations are just like the jackpot,” says Jeremy Kamil, an immunologist at Louisiana State University.
The Centers for Disease Control and Prevention is monitoring greater than a dozen omicron subvariants proper now, together with BF.7, BQ.1 and BQ.1.1, a few of which seem like among the many most immune-evasive but.
Fortunately, the immunity folks have constructed up from vaccination and an infection nonetheless seems to be defending most from severe sickness and dying.
But the newer extremely contagious omicron subvariants might assist drive one more surge. They additionally give the virus many possibilities to breed, mutate and evolve much more.
A household tree nonetheless filled with surprises?
While all this sounds dire, omicron’s lengthy interval of dominance is giving some scientists some hope.
The virus might, in a single comparatively optimistic situation, preserve evolving this fashion for a very long time, drifting in additional refined evolutionary instructions just like the flu, with out sudden shifts in the way it behaves that make it extra harmful.
“The proven fact that we have maybe stepped out of a part [in the pandemic] the place we’re getting fully new viruses from completely different components of the tree sweeping in and dominating is likely to be an indication that we’re shifting in direction of a extra form of secure future for the virus,” Hodcroft says.
But that will imply massive numbers of individuals would nonetheless catch the virus. Many would nonetheless get severely in poor health, die, or be left with lengthy COVID. And as a result of the virus continues to be so new, it is not possible to know the way the virus may evolve sooner or later, specialists inform NPR.
“We are actually coping with a very novel virus right here,” says Kristian Andersen, an immunologist at Scripps Research. “We do not know what number of different paths this specific virus may need. We simply do not know at this stage.”
There’s no option to rule out, for instance, the chance {that a} dramatically completely different variant may emerge but once more, maybe after simmering inside somebody with a compromised immune system that may’t drive out the virus. That lets the virus extensively work together with the human immune system and discover much more advantageous mutations.
“I assure you that there are individuals who have been persistently contaminated with delta and alpha who’ve some actually bizarre combos of mutations,” says Michael Worobey, an evolutionary biologist on the University of Arizona. “And I’m totally ready for a delta-based or alpha-based omicron-like occasion the place a type of zombie viruses that is been cooking away inside somebody emerges.”
