comparison between these two variants of the coronavirus

(CNN) – Omicron, the new variant of the coronavirus, with its many mutations and apparently rapid spread in South Africa, is causing concern to scientists and government authorities.

But doctors want to remind Americans that they are already facing a fairly large variant of coronavirus, and it is delta.

Delta was able to spread throughout the United States in a matter of weeks in early summer, changing the landscape of a country that was deploying vaccines and hopes just as quickly.

“At the end of June, the seven-day moving average of reported cases was about 12,000. On July 27, the seven-day moving average of cases reached more than 60,000. This rate of cases was more like the rate of cases that we had seen before the vaccine was widely available, “says the US Centers for Disease Control and Prevention (CDC) on its website. “The delta variant is highly contagious, more than twice as many as previous variants.”

According to the CDC, the delta variant currently accounts for more than 99% of coronavirus cases that are genetically sequenced in the United States.

Omicron vaccine could be approved in about 4 months 0:43

Whether omicron will outperform Delta remains to be seen, but it will be tough.

“We still have, of course, in the US, a serious rise in the delta variant. We should think about it,” Dr. Francis Collins, director of the National Institutes of Health, told CNN on Monday.

According to Johns Hopkins University (JHU), the United States has an average of 70,094 new cases of covid-19 and 730 deaths per day. And the JHU states that 75% of beds in US intensive care units are occupied, of which 15% correspond to patients with covid-19.

Comparison between omicron and delta

There is much talk about the 50 mutations that characterize the omicron variant, 32 of them in the spike protein, which is the crown-shaped structure that covers the surface of the virus and attaches itself to human cells in order to infect them.

But delta has its own constellation of terrifying mutations, which have made it the worst version of the virus yet. It sprints through populations, replacing more worrisome variants that carry mutations that should allow them to bypass the effects of vaccines – like the beta variant, for example.

Robert Garry, a virologist at Tulane University, performed a direct comparison of the observed mutations in delta and omicron.

Ómicron has “one part of them at a time,” Garry told CNN. “But we’ve already seen that kind of leap in evolution,” he added.

“There are definitely hot spots where this virus likes to mutate right now,” he said. But the fact that there are many mutations does not necessarily mean that they will add to a more harmful virus.

“We still don’t know what all these changes are going to do together for the things that matter to this virus,” Garry said.

But you don’t see many major mutations that can make the omicron version more contagious than the delta.

“The ones that could affect transmissibility, that is, I don’t see many that give it a really strong advantage over delta,” he said.

“That is really the big question. When you enter a population that has a delta, will it compete more than it or not?”

Omicron vaccine could be approved in about 4 months 0:43

Other genetic experts also note that omicron does not carry some of the changes that helped make delta so contagious.

“Given that omicron lacks many of the non-spike-related mutations that appear to contribute to the increased delta capacity, I wouldn’t be surprised if its intrinsic transmissibility is similar to gamma,” Genome and Genome Scientist Trevor Bedford said on Twitter. epidemiologist at the University of Washington and the Fred Hutchinson Cancer Center in Seattle.

He referred to a September study by researchers at the Broad Institute who found at least three mutations in the delta variant that they say appear to contribute to making it more transmissible.

Some of the mutations that increase transmissibility are also seen in variants that went extinct, such as a so-called kappa.

Protection against covid-19

Garry sees mutations that could help omicron evade the body’s immune response, especially from previous infections.

“It is likely to be elusive immune. So is delta, and before alpha and beta. Should we be working on a specific vaccine? Yes,” he said.

The immune response elicited by vaccination is broader than that produced by a natural infection, so vaccinated people can continue to be protected against serious disease, according to doctors.

“Your best protection against delta is to get vaccinated, and if you’ve already been vaccinated and it’s been six months since you got vaccinated with Pfizer or Moderna, put on the booster, or two months from J&J, put on the booster,” Collins told CNN.

“That was already a reason, but now omicron is added to the mix,” he said. “And we believe that this new variant, which will probably reach our shores, will also be something that vaccines and reinforcements can help with.”

The CDC strengthened its guidance on boosters Monday, saying that all adults should receive boosters six months after completing the first two doses of the Moderna or Pfizer / BioNTech vaccine and two months after receiving the single-dose vaccine from Johnson & Johnson.

And there is no known mutation that can cause a virus to bypass precautions like face masks, hand washing, and physical distancing. Even if a mutation helps make a virus more viable as an airborne pathogen, better ventilation can help prevent transmission.

CNN’s Naomi Thomas and Deidre McPhillips contributed to this article.

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