What Are the Differences between Omicron and Other Coronavirus Variants?

Anthony S. Fauci, a senior US infectious disease official, said in a statement on November 30, 2021 that the newly identified Omicron COVID-19 variant could be highly contagious and less susceptible to existing vaccines than other variants, but that it was still too early to know how it behaves compared with the Delta variant.

Fauci Explains the Differences between Variants

Speaking at a COVID-19 briefing at the White House, Fauci said there were "some very unusual changes" in the genome of this new variant showing that it was different from any variant seen so far.

Fauci said, "This mutation profile is very different from other variants of interest and concern, and although some mutations are also found in Delta, this is not Delta." He said, "These mutations are associated with increased transmissibility and immune evasion."

Omicron is the fifth COVID-19 variant of concern.

Omicron, first identified in South Africa, has so far been identified in 20 countries. There are no known cases in the United States yet, but it has been detected in Canada.

Fauci said Omicron has more than 30 mutations in its spike protein, the part of the virus that binds to human cells.

The mutation profile of the Omicron variant, code-named B.1.1.529, can be seen below:

Cross-Protection Provided by Additional Vaccine Doses

Although the mutations appear to increase the transmissibility of this variant, Fauci said it was too early to know how it compares with Delta. And according to Fauci, the vaccines will probably provide some protection, even if they are not as effective against Omicron.

"Remember, as with other variants, although partial immune escape may occur, vaccines — especially additional booster doses — give you an antibody level that provides some degree of cross-protection, particularly against severe disease, even with variants such as Delta" he said.

Fauci said, "When we say that these mutations suggest a reduction in vaccine-provided protection and some degree of immune evasion, we can still reasonably conclude from our experience with Delta that you will not eliminate all protection against this particular variant."

So far, there is no reason to believe that Omicron will cause more severe disease than other variants of concern.

In other words, although Omicron certainly transmits/spreads rapidly, it does not appear to cause more severe disease.

He advised people to continue wearing masks, washing their hands and avoiding crowded indoor spaces. Most importantly, he advised everyone to get their vaccinations and additional booster doses.

One thing has become clear over the last 20 months: We cannot predict the future, but we can prepare for it. We have far more tools to fight the variant today than we had at this time last year.

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