Omicron: How transmissible is the new variant and can it evade vaccines?

WHO says overall global risk related to the new variant is ‘very high’, while governments are doubling down on need for vaccinations

Shweta Sharma
Tuesday 30 November 2021 10:08
<p>WHO says omicron variant will likely spread internationally and could have severe consequences in some areas</p>

WHO says omicron variant will likely spread internationally and could have severe consequences in some areas

The emergence of the new omicron variant of coronavirus has prompted public concern around the world and sent scientists racing to examine its potential impact.

So far more than 150 infections of the omicron variant have been detected in more than a dozen countries across the world, with the highest number — 77 cases — reported in South Africa.

In an address from the White House on Monday, US president Joe Biden said omicron is a “cause for concern, not a cause for panic” while urging people to keep getting their vaccines and booster shots.

The heavily mutated variant, whose scientific name is B.1.1529, poses a “very high risk” of infection and is likely to spread internationally, bringing potentially “severe consequences” for some communities, the World Health Organisation said on Monday.

Is omicron more transmissible than the delta variant?

While it will take weeks to have an evidence-based understanding of the impact of the new variant, what is so far known for sure is that it carries an “unprecedented” and “very unusual” number of mutations to its genome.

Omicron has 32 mutations in its spike protein, compared to the original SARS.CoV.2 virus that emerged in Wuhan in late 2019. For comparison the delta variant, which rapidly became dominant around the world, has between 11 to 15 mutations in its spike protein, according to the CDC.

“Omicron has an unprecedented number of spike mutations, some of which are concerning for their potential impact on the trajectory of the pandemic,” the WHO said. “The overall global risk related to the new variant… is assessed as very high.”

The 32 mutations include E484A, K417N and N440K, which are known to help the virus to escape detection from antibodies.

Christian Althaus, a computational epidemiologist at the University of Bern, said in a series of tweets that the variant has an estimated growth advantage of 0.38-0.43 per day, which translates to transmissibility of 280 per cent more than the delta variant.

The epidemiologist said he expects “partial immune evasion to be the main driver of the observed dynamics, but increased transmissibility cannot be ruled out so far”.

Can omicron cause more serious illness?

While the WHO says it is still unclear whether or not omicron causes more severe illness or whether it is more deadly than previous variants, no deaths have been reported as being linked to omicron so far.

In South Africa, which first raised alarm over the new variant and detected the first cases on 9 November, the average number of daily cases of all Covid variants jumped to about 1,600 last week from about 500 the previous week, following 275 infections a week before that, president Cyril Ramaphosa said Sunday.

Raina MacIntyre, professor of global biosecurity at the University of New South Wales in Sydney told Time: “So far, the virus has not mutated to become less severe — in fact the opposite.”

Experts have noted that in South Africa the new variant has mostly infected students, who are younger and tend to have milder symptoms, amid low vaccination rates and a lower average age across the population in South Africa. They cautioned about drawing conclusions from South Africa and throwing the term “mild” around, given the demographics in question and the fact that hospitalisations are still rising, with there still being time for the infections to progress from mild to severe.

Can it evade vaccines?

Omicron has some 50 mutations in all, out of which 32 pertain just to the spike protein — the part which the virus uses to gain entry to human cells. The new variant is now radically different to the original that emerged in Wuhan, China, meaning that vaccines which were designed to target the spike protein of the original variant may not be as effective.

That still does not mean vaccines will have no impact on omicron — the WHO says it is too early to draw such conclusions, and that real-world studies are ongoing to establish how the new variant interacts with fully vaccinated individuals.

On Monday, the CDC strengthened its recommendation on booster doses for individuals who are 18 years and older amid the renewed threat from omicron.

"The recent emergence of the omicron variant further emphasises the importance of vaccination, boosters, and prevention efforts needed to protect against Covid-19," CDC Director Dr Rochelle Walensky said in a statement.

"Early data from South Africa suggest increased transmissibility of the omicron variant, and scientists in the United States and around the world are urgently examining vaccine effectiveness related to this variant. I strongly encourage the 47 million adults who are not yet vaccinated to get vaccinated as soon as possible and to vaccinate the children and teens in their families as well because strong immunity will likely prevent serious illness,” she added.

How widely has omicron spread across the world?

Omicron has triggered a global alarm with countries scrambling to issue travel advisories to seal their borders with South Africa, where the first cases of the new variant were detected. Between them, South Africa and Botswana have recorded almost 100 cases.

But it may already be too late to prevent omicron’s international spread — the UK has already detected nine cases, as of midday on Tuesday 30 November, with the Netherlands and Portugal reporting 13 cases each. Cases have also been reported elsewhere across Europe including in Germany, Denmark, Austria, Italy and Belgium.

The US is yet to confirm a case, but has issued a travel advisory for foreigners coming from southern African nations.

Japan reported its first case on Tuesday morning, while there have been several cases in Canada, Hong Kong, Israel and Australia. Japan and Israel have shut their borders entirely to foreigners, while Hong Kong has issued even stricter rules for travellers than the rigorous quarantine measures it already had in place.

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