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Understanding omicron: How the latest coronavirus variant, now in the US, is mutating and spreading

The new coronavirus variant changes its infection-wielding spike proteins – and forces comparison to fast-moving delta strain. Here's how it works.

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At least five states have discovered people testing positive for the omicron variant, a new, possibly vaccine-resistant strain of the coronavirus.

Omicron has raised concern worldwide about a surge of infections if vaccines are less effective against it.

The first U.S. case, on Dec. 1, involved an unidentified person who traveled from South Africa, where the variant was first identified on Nov. 22. That person tested positive for COVID-19 on Nov. 29.

The second case, in Minnesota on Dec. 2, was a Hennepin County man who recently visited New York City, according to the Minnesota Health Department. Other cases were subsequently reported in New York, Colorado and Hawaii.

The first U.S. confirmation came from Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases. Fauci said the person was fully vaccinated and has mild symptoms, "which are improving at this point."

Though details are still emerging, omicron's rapid spread from South Africa to Europe and beyond has researchers wondering if it will be as bad or worse than the delta variant. Delta was first identified in India in 2020 and accounts for 99% of recent COVID-19 cases in the USA, according to the Centers for Disease Control and Prevention.

It probably will be a few weeks before we learn how serious omicron is, but there are a few things we do know.

Omicron was officially identified Nov. 25 in South Africa and has been confirmed in Canada, Britain, Germany, Israel, Australia and other countries.

However, Dutch health officials said Tuesday that two omicron cases were found before South Africa's announcement. This indicates the new variant was already spreading in Europe.

Monday, President Joe Biden cautioned that the variant was a “cause for concern, not a cause for panic," and he asked Americans to get vaccinations or boosters and wear masks in public places.

The World Health Organization warned the "likelihood of potential further spread of omicron at the global level is high," which could result in "severe consequences."

All viruses change, or mutate, as they replicate. The omicron variant, known as B.1.1.529, appears substantially different from the original coronavirus, with 50 genetic changes.

Among them are 26 to 32 changes in the spike proteins, the jagged points that cover the surface of the coronavirus. The virus uses them to enter and infect cells.

COVID-19 mRNA vaccines, such as the Moderna and Pfizer-BioNTech versions, target spike proteins to prevent infection. Changes in COVID-19 spike proteins could make vaccines less effective, but there’s no evidence that omicron can overcome the protection of vaccination.

On Nov. 26, the WHO designated omicron a “variant of concern,” the first such designation since the delta variant appeared in October 2020.

The designation came less than a month after omicron was first detected. The five variants of concern, dates of discovery and WHO dates of designation:

  • Alpha: September 2020 | Dec. 18, 2020
  • Beta: May 2020 | Dec. 18. 2020
  • Gamma: November 2020 | Jan. 11, 2021
  • Delta: October 2020 | May 11, 2021
  • Omicron: November 2021 | Nov. 26, 2021

Though it's unclear whether omicron originated in South Africa, the variant reignited discussion on variations coming from areas with low vaccination rates. Researchers say the virus "is much more likely to mutate in places where vaccination is low and transmission high," CNN reported.

On Monday, the CDC upgraded its recommendations on COVID-19 booster shots. The agency advises that all adults get booster shots:

  • Six months after the first two doses of Moderna vaccine.
  • Six months after the first two doses of Pfizer/BioNTech's vaccine.
  • Two months after getting Johnson & Johnson's single-dose vaccine.

In response to omicron's discovery, the United States restricted travel from South Africa and seven other African nations Nov. 26. The ban doesn't apply to U.S. citizens or permanent residents, but a negative coronavirus test will be needed before they are allowed entry.

CONTRIBUTING: Elizabeth Weise

SOURCE USA TODAY Network reporting and research; The Associated Press; Centers for Disease Control and Prevention; World Health Organization

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