Why Omicron quickly became a variant of concern

Enlarge / That's a lot of mutations. (credit: Stanford)

On Friday, the World Health Organization officially named a new version of the SARS-CoV-2 virus a variant of concern, and attached the Greek letter omicron to the designation. The Omicron variant is notable for the sheer number of mutations in the spike protein of the virus. While Omicron appears to have started spreading in Africa, it has already appeared in European countries like Belgium and the UK, which are working to limit its spread through surveillance and contact tracing.

As of now, the data on the variant is very limited; we don't currently know how readily it spreads compared to other variants, nor do we understand the degree of protection against Omicron offered by vaccines or past infections. The new designation, however, will likely help focus resources on studying Omicron's behavior and tracing its spread.

Many changes

While the Delta variant's version of spike has nine changes compared to the virus that started the pandemic, Omicron has 30 differences. While many of these haven't been identified previously, a number of these have been seen in other strains, where they have a variety of effects. These include increasing infectiveness of the virus, as a number of the changes increase the affinity between the spike protein and the protein on human cells that it targets when starting a new infection.

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