Why Might Omicron Be Dangerous, and How Is It Different to Other COVID Variants?

Scientists are assessing the potential threat posed by the Omicron variant of COVID, which has been capturing headlines worldwide over the past few days.

The variant was classified as a variant of concern (VOC) by the World Health Organization (WHO) on Friday after scientists had been voicing concern about it for several days.

At the moment nothing is certain about Omicron, including how fast it spreads, how effective vaccines are against it, and whether it causes more severe disease compared with other variants.

No other variant in the history of the pandemic has been classified as a VOC so soon after its discovery; the first confirmed Omicron case was on November 9, 2021, according to the WHO. Delta, the variant that was effective enough to become largely dominant worldwide, wasn't classified as a VOC for months following its first reported case.

Scientists have been saying that Omicron is different to other variants because it has a large number of mutations—up to 32 in its spike protein alone—that could make it effective at spreading and resisting immunity.

Other variants, like Delta and Alpha, have also shown mutations to their spike proteins. But the number found in Omicron is higher than any other variant so far, Tom Peacock, a research associate at the Department of Infectious Diseases at Imperial College London (ICL), said in a recent Q&A.

So why could that make it more dangerous? When our immune systems target COVID, they produce little molecules called antibodies that essentially fit onto the spike protein of the virus and prevent it from entering our cells and making us sick.

But when the virus mutates, the spike protein changes. That means antibodies are no longer able to attach to it as well as before. The more changes there are to the spike protein, the harder it may be for existing antibodies to work.

Antibodies are produced either by vaccines or previous infections. The concern is that existing antibodies might not be as compatible with Omicron as they are with other variants, which would mean that Omicron would make someone sick more easily even if they had previously had COVID or a vaccine.

Tests Are Ongoing

Peacock and others predict that this might be the case, but it should be noted that it isn't known how well the current vaccines work against the variant. Assessments are ongoing.

Another unconfirmed danger posed by Omicron is its potential to spread faster than other variants. It isn't clear if this is the case, but Peacock noted in the Q&A that there are "important" changes in another region of Omicron's spike protein that are associated with increased transmissibility.

Daily cases more than tripled in South Africa, where some of the earliest examples of Omicron were found, between Tuesday and Friday last week, with most new cases apparently caused by the new variant, according to the Financial Times, which cited early testing results.

The WHO noted that work is underway to understand Omicron's role in the increase in South African cases and its potentially higher transmissibility.

COVID test
A COVID test being prepared by a health worker at Sydney International Airport, Australia, on November 28, 2021. Scientists have voiced concern about the Omicron variant. James D. Morgan/Getty