Omicron: What Is the Difference Between ‘Variant of Interest' Vs. ‘Variant of Concern?'

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As the World Health Organization announces that omircon has been classified as a "variant of concern," many are asking about the difference between this categorization and a "variant of interest."

WHO Health Emergencies Programme COVID-19 Technical Lead Dr. Maria Van Kerkhove said early evidence on omicron, known by the technical term B.1.1.529, shows that the variant has a large number of mutations, some of which have concerning characteristics.

Omicron has also shown to have an increased risk of reinfection compared to other highly transmissible variants, indicating that people who contracted COVID and recovered could be more subject to catching it again with this variant.

According to the Centers for Disease Control and Prevention, however, variants of the coronavirus were expected.

"Viruses constantly change through mutation, and new variants of a virus are expected to occur," the CDC's website reads. "Sometimes new variants emerge and disappear. Other times, new variants persist. Numerous variants of the virus that causes COVID-19 are being tracked in the United States and globally during this pandemic."

Variants are categorized into three categories: (1) "variants of interest," (2) "variants of concern" and (3) "variants of high consequence."

The CDC states that a variant is classified as a variant of interest if it shows "specific genetic markers that have been associated with changes to receptor binding, reduced neutralization by antibodies generated against previous infection or vaccination, reduced efficacy of treatments, potential diagnostic impact, or predicted increase in transmissibility or disease severity."

"We will probably have a variant of what we call a variant of interest identified every few weeks," Chicago Department of Public Health Commissioner Dr. Allison Arwady said Tuesday. "Like that's how this virus works. Variants of interest just mean we've seen a number of the same genetic mutations emerge and scientists around the world are on the lookout for it every single time. A virus anywhere in the world gets this genetic sequence, it gets updated into a database that's shared internationally, so we can really see what's emerging. When a variant of interest emerges, it says, 'Oh, this is something we should watch a little bit.'"

A variant of concern is one in which "there is evidence of an increase in transmissibility, more severe disease (e.g., increased hospitalizations or deaths), significant reduction in neutralization by antibodies generated during previous infection or vaccination, reduced effectiveness of treatments or vaccines, or diagnostic detection failures," according to the CDC.

"Once we see a variant of interest clearly have an impact, meaning it is more contagious, it might be evading a treatment, it's clearly making people sicker - that makes it into a variant of concern," Arwady said.

Variants of concern, which include alpha, beta, delta and now omicron, have shown to spread more easily, cause more serious disease, or dent the effectiveness of vaccines and other COVID-fighting tools. They’re more worrying than the variants of interest — like mu and lambda — that have affected aspects like transmissibility and severity of the disease but aren't as transmissible.

Finally, a variant of high consequence "has clear evidence that prevention measures or medical countermeasures have significantly reduced effectiveness relative to previously circulating variants." Or, as Chicago's top doctor put it, a variant in which "the vaccine was not working very well."

Currently there are no variants of high consequence.

"I would say if something became a variant of high consequence that would be a big deal," Arwady said, adding that such variants are ones in which "the vaccine was not working very well."

As of Saturday, no cases of omicron have officially been detected across the U.S., according to health officials. The Chicago Department of Public Health noted, however, that they are "don't know" if the variant has reached America yet.

Omicron has thus far been seen in travelers to the U.K., Belgium, Hong Kong and Israel, as well as in southern Africa.

For what we know so far on the omicron variant, click here.

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