Scientists around the world are racing to understand more about the latest COVID-19 variant, dubbed Omicron, which has sparked international travel bans and stricter quarantine measures.
On Saturday, the World Health Organization (WHO) classified Omicron as a variant of concern, amid fears it could potentially be more transmissible and able to evade immune protection.
Health authorities in South Africa first raised the alarm about the new variant when a doctor treating COVID-19 patients in early November found their symptoms didn't fit the classic Delta variant profile.
In recent weeks, the Omicron variant has been linked to a surge in COVID case numbers in the Gauteng province of South Africa, which takes in the cities of Pretoria and Johannesburg.
Is it inevitable the Omicron variant of COVID-19 will spread like Delta?
The emergence of the Omicron variant of coronavirus shows Africa needs greater access to vaccines, experts say. There are also warnings we shouldn't give up masks, social distancing or contact tracing in Australia.The federal government on Saturday announced that non-Australian citizens who have been in nine countries in southern Africa where Omicron has been detected are barred from entering Australia.
The WHO and medical experts around the world have cautioned people not to panic, and stressed that very little is known about the Omicron variant.
While there's still a lot to learn, here's a little bit of what we do (and don't) know so far.
Why is Omicron a variant of concern?
The WHO's decision to classify Omicron as a variant of concern is based on several "concerning" mutations the variant has that may change the way it behaves.
"Preliminary evidence suggests an increased risk of reinfection with this variant, as compared to other variants of concern," the WHO said in a statement.
In other words, people who previously had COVID-19 could become reinfected more easily with Omicron.
The WHO also says the new variant "has been detected at faster rates than previous surges in infection, suggesting that [it] may have a growth advantage".
PM 'fully supports' action by NSW and VIC with Omicron fears growing
The Prime Minister Scott Morrison has said he 'fully supports' the action taken by New South Wales and Victoria amid growing fears over the super-contagious Omicron strain of Covid-19. But Dr Paul Griffin, Director of Infectious Diseases at Mater Health in Brisbane, said it was still too early to judge the risks of Omicron.'I don't think we're back to square one. I mean, I think a lot of us thought this is what this virus is going to keep doing, going to keep evolving and we are going to keep finding new variants,' he told ABC.
Of particular concern is the fact Omicron has more than 30 mutations on its spike protein, more than double the number carried by Delta.
The spike protein is what the virus uses to attach to human cells, and what COVID vaccines teach our immune system to recognise and target.
"The places that [the variant] has changed are places that we know from previous variants are dangerous spots," epidemiologist Nancy Baxter told ABC News Breakfast.
"They either make the virus more transmissible, or make it easier for the virus to evade the vaccine or natural immunity."
That being said, it's too early to say how this particular combination of changes — which have been described as an "unusual constellation of mutations" — will behave.
"Right now, researchers are getting together to understand where these mutations are and what that potentially may mean for our diagnostics, our therapeutics and our vaccines," WHO COVID-19 technical lead Maria Van Kerkhove said last week.
TWO confirmed cases of fears Omicron Covid strain are found in Sydney
NSW Health announced on Sunday urgent genomic testing had confirmed two overseas travellers have the South African variant of the virus.NSW Health confirmed on Sunday urgent genomic testing found the two travellers who touched down in Sydney on Saturday night have the new strain.
"It will take a few weeks for us to understand what impact this variant has. There's a lot of work that is underway."
Is Omicron more transmissible?
While some of Omicron's mutations have been associated with increased transmissibility, the jury is still out on whether it's more contagious than other variants.
"The number of people testing positive has risen in areas of South Africa affected by this variant, but epidemiologic studies are underway to understand if it is because of Omicron or other factors," the WHO said on Sunday.
The recent surge in cases in South Africa, particularly in its Gauteng province, suggests Omicron may have a competitive advantage over Delta.
"We are seeing that it's probably very infectious, not only from the story coming out of southern parts of Africa, but also we are seeing fully vaccinated people arriving in countries like Australia who are positive," Catherine Bennett, Deakin University's chair of epidemiology, told ABC News.
So far, the new variant has been detected in multiple countries, including Israel, the UK and Canada.
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NSW Health confirmed on Sunday two travellers who touched down in Sydney on Saturday night have the new South African Covid variant, Omicron, which is feared to be more transmissible than Delta.NSW Health confirmed on Sunday urgent genomic testing found two travellers who touched down in Sydney from southern Africa on Saturday night have the new strain.
Is Omicron more deadly than other variants like Delta?
As there are still only relatively few confirmed Omicron cases, we don't know if it's more lethal or causes more severe disease than the Delta variant.
The WHO states, "there is currently no information to suggest that symptoms associated with Omicron are different from those from other variants".
South African doctor Angelique Coetzee, who first spotted the new variant in her patients, said Omicron tended to produce milder symptoms.
She also told RN Breakfast while she saw patients with fever, headaches, body aches and nausea, no-one showed symptoms commonly seen with the Delta variant: "No loss of smell, no loss of taste, no severe congestion in their sinuses or any of that."
The most severe case of the Omicron variant she's seen so far was in a six- or seven-year-old child, who had a high fever and fast heart rate.
Dr Coetzee prescribed a course of antiviral medication and followed up two days later.
"The child was … much, much better. There was no fever, their pulse dramatically dropped to normal, and that was the worst patient I have seen," she said.
That's not to say more patients with severe disease won't start showing up, Dr Coetzee added.
"Nearly one in six people [tested today] was positive … so we will see by the end of this coming week how many of them are developing severe symptoms."
Everything we know about the Omicron Covid strain so far
Epidemiologist Nancy Baxter, who is the head of Melbourne School of Population and Global Health at University of Melbourne, said 'there's reason to be concerned but no reason to panic'.Epidemiologist Nancy Baxter, who is the head of Melbourne School of Population and Global Health at University of Melbourne, said 'there's reason to be concerned but no reason to panic' about the new variant.
Some South African physicians are already reporting young adults with moderate to severe disease caused by the Omicron variant.
And how the new variant acts in more vulnerable populations, such as older people, is still unknown. Many early infections have been in younger people.
In terms of hospitalisation, South Africa is seeing an uptick in people being admitted, but, according to the WHO, "this may be due to increasing overall numbers of people becoming infected, rather than a result of specific infection with Omicron".
There have been no reported deaths due to the Omicron variant yet.
Will current COVID treatments work against Omicron?
We don't know yet.
But the good news is at least some of them should.
Antiviral medications, such as molnupiravir (which is not yet approved for use in Australia) and remdesivir, stop the virus from replicating in our cells instead of targeting the proteins in the spike. They're likely to work as well against Omicron as they do against other variants.
People who develop severe disease typically struggle against their own immune system, which goes into overdrive in response to an infection and doesn't switch off.
Medications that quell that overreaction, such as corticosteroids and drugs that block a particular inflammatory molecule, "will still be effective for managing patients with severe COVID-19", according to the WHO.
"Other treatments will be assessed to see if they are still as effective given the changes to parts of the virus in the Omicron variant."
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The country has delayed the gradual re-opening of the international border until December 15 while experts scramble to answer these crucial questions.Prime Minister Scott Morrison has delayed the gradual re-opening of the international border until December 15 while experts scramble to work out how dangerous the new stain is.
That's because some treatments, such as monoclonal antibodies, are specific to the virus — the spike protein in particular.
Change the shape or structure of the spike protein, and a drug may not be able to do its job as well — and the Omicron variant has 32 mutations on its spike protein.
So there are studies in train to see how well treatments work against the Omicron variant, with more information expected "in the coming days and weeks", the WHO said in a statement.
Do the vaccines work against Omicron?
COVID vaccines work by training the body's immune system to recognise the SARS-CoV-2 virus's spike protein.
So with dozens of mutations on that all-important vaccine target, will the current suite of vaccines — Australia has three approved vaccines in Pfizer, AstraZeneca and Moderna — be rendered ineffective against the Omicron variant?
Professor Bennett says it's too early to tell, but it's likely we'll still be protected against severe disease and death.
"The two people who arrived in Australia [on Sunday] were fully vaccinated, but we know the vaccines have stood up against other variants, particularly for severe illness," she said.
"So I think we should be confident that's still the case."
She said South Africa had low rates of vaccination — only around a quarter of the population is covered — so it would take time to evaluate vaccine effectiveness against the Omicron variant.
We should know within weeks how well the COVID vaccines stack up, she added.
We don't know if a third dose of vaccine will help against Omicron either, but this morning, Health Minister Greg Hunt said he asked Australia's expert immunisation panel to review the booster shot timeframe.
Australia's vaccine stocks could accommodate fast-tracking them if it was recommended, he added.
If need be, the next iteration of COVID vaccines can be tweaked to better target the Omicron variant, along with any others that may appear.
Pfizer and BioNTech, for instance, claim they can adapt their mRNA vaccines to so-called "escape variants" and ship them out within 100 days.
Plus there are non-vaccine interventions, Professor Baxter says, "like mask wearing, social distancing and ventilation — those things will work against any variant".
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"We have a lot of tools, we've learned a lot, so people should be concerned, but no-one should be panicking right now."