Omicron virus: What we know so far about the new Covid strain

Just as Australians dared hope we may finally be putting the worst of the Covid-19 pandemic behind us, a new mutation of the virus has emerged. So what is Omicron and what does it mean?

Just as life looked like it might be returning to something resembling pre-pandemic normal, the World Health Organisation (WHO) named Omicron as a new variant of concern to the SARS-CoV-2 virus in late November.

It’s far from welcome news and a sharp reminder to the world the pandemic is not over, but what does it mean for a country like Australia, where the eligible population is more than 86 per cent fully vaccinated and rising?

What is Omicron and why is it such a concern?

Omicron, named after the 15^th letter of the Greek alphabet, is a variant of the SARS-CoV-2 virus, and was first reported to the WHO from South Africa.

It is likely to have come from a single patient who was unable to beat the virus, according to Murdoch University Health Futures Institute and centre director Professor Jeremy Nicholson.

“This variant almost certainly emerged in an immunocompromised individual who could not clear the original infection,” Prof Nicholson says.

“Most likely an unvaccinated HIV patient in South Africa where the virus can replicate and evolve.”

While the emergence of a new variant is worrying, it’s not unexpected, according to Dr Deborah Cromer, group leader of infection epidemiology and policy analytics at the Kirby Institute.

“Viruses constantly mutate and take on new forms,” Dr Cromer says.

It is not yet known if Omicron is more severe or transmissible than the Delta strain, but Omicron is a concern because of the “very unusual” number of its mutations, explains Curtin University International Health Professor Jaya Dantas.

“Omicron is the most heavily mutated variant of concern discovered so far,” Prof Dantas says.

“Genomic testing has indicated there are 50 mutations overall and more than 30 on the spike protein, which is the target of most vaccines and the key the virus uses to unlock the doorway into our body’s cells.

“The receptor-binding domain (the part of the virus that makes first contact with our body’s cells) has 10 mutations in Omicron compared to just two for the Delta variant.”

I’m fully vaccinated – do I need to be worried?

Fortunately in Australia, the vast majority of the eligible population is fully vaccinated.

But it is still not known how effective our current vaccines will perform against Omicron, CSIRO special health advisor Dr Rob Grenfell explains.

“The vaccines work on stimulating the immune system by exposure to a replicant of the viral spike protein,” Dr Grenfell says.

“This immunity has been demonstrated to be strong against emerging variants to date.

“It is expected that the current vaccines will continue to provide immunity against the Omicron variant – the question is how strong this may be.”

Australian National University infectious diseases specialist Associate Professor Sanjaya Senanayake says only field experience can provide a true understanding of how well vaccines may work against the new variant.

“There are (laboratory) tests where stored serum in vaccinated people can be tested against the virus to see how strong the neutralising antibody responses are,” Assoc Prof Senanayake says.

“While it’s not the same as seeing how vaccinated people respond to the variant in real life, it can give some idea if the vaccine will have some effect against Omicron.”

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Will a Covid-19 vaccine booster help my immunity to Omicron?

Even though vaccine efficacy against Omicron is not yet fully understood, vaccination remains an important part of the pandemic response, according to Monash University Malaysia virologist Dr Vinod Balasubramaniam.

“Getting vaccinated against Covid-19 is the strongest form of protection,” Dr Balasubramaniam says.

“It should therefore be our main goal to slow down virus spread by adhering to the existing hygiene and speeding up the vaccination including the booster doses process.”

Dr Cromer says booster shots increase immunity against the virus.

“What we have seen is that higher levels of immunity are required to combat new variants (both to protect against any infection and severe disease).

“Therefore, boosting immunity overall will help in combating disease from emerging variants.”

Head of Biosecurity at the Kirby Institute Professor Raina MacIntyre believes Australia should be speeding up its third dose coverage against Covid.

“The booster can be given any time from two to six months after the second dose,” Prof MacIntyre says.

“We should also be ensuring supply of the paediatric vaccine formulations and a recommendation for kids five to 11 years ASAP.

“And we should be talking to companies and making procurement plans for Omicron-matched boosters as well as the two new promising antivirals.”

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Why vaccine equity matters

Dr Balasubramaniam says the emergence of Omicron is a reminder of the importance of global vaccination against Covid-19.

“Every time the virus reproduces inside someone who is not vaccinated, there’s a chance of it mutating and a new variant emerging,” he says.

“This is a numbers game. It’s a random process, a bit like rolling dice. The more you roll, the greater the chance of new variants appearing.

“The main way to stop variants is equal global vaccination.

“We must get vaccines to these people as quickly as possible (especially in countries that are behind in vaccination rate), both to help the people there who are vulnerable but also to stop new variants from emerging.”

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Will there be a return to lockdowns?

After the past two years being in and out of lockdown, the idea of ever having to go back there may seem intolerable to many Australians.

But right now, the answer to whether lockdowns will return is it’s too early to tell, according to the experts.

“This will only be able to be answered once we have a better understanding of how much of a concern the variant is,” Dr Grenfell says.

“If it is more infectious or more severe, then we may need to use all the public health tools necessary to reduce the spread.”

Prof Dantas believes learnings from the past 20 months put us in a much better position than at the start of the pandemic.

“Lockdowns should be minimised with the use of public health measures and using self-isolation where possible but all will depend on the severity of the disease of this variant,” she says.

How can I reduce my risk against Omicron?

The same public health measures we’ve been practising since the pandemic began still apply:

• Good hand hygiene.
• Wearing a mask.
• Social distancing.
• Getting tested if you’re unwell.
• Quarantining active cases.
• Getting vaccinated.
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Written by Claire Burke.