The World Health Organisation has declared a new coronavirus variant to be "of concern" and named it Omicron

This is the new and potentially more transmissible coronavirus variant first identified in South Africa, and has prompted a fresh round of travel restrictions across the world and raised concern about what may be next in the pandemic.

New Zealand has joined Australia, in immediately banning incoming travel from nine South African countries.

While scientists say there is reason to be concerned over the variant, they stress there is still a lot we don't know -- including whether the variant is indeed more contagious, whether it causes more severe disease or what its effects on vaccine efficacy may be.

"While this is concerning, as the WHO has indicated, I do think that we have to step back and wait for the science on this," epidemiologist Dr. Abdul El-Sayed told CNN.

What’s known and unknown about Omicron?

Scientists know that omicron is genetically distinct from previous variants including the beta and delta variants, but do not know if these genetic changes make it any more transmissible or dangerous. So far, there is no indication the variant causes more severe disease.

It will likely take weeks to sort out if omicron is more infectious and if vaccines are still effective against it.

New Zealand based Cambridge University consultant clinical virologist Dr Chris Smith talked to RNZ's Kim Hill about what Omicron might mean.

"It's a variant of concern, which basically means it goes up a notch in how we deal with it, but it doesn't mean it's a foregone conclusion it's going to be a problem."

Dr Smith clarified, that it is too early to know if it will be more dangerous than existing variants like Delta.

Peter Openshaw, a professor of experimental medicine at Imperial College London said it was “extremely unlikely” that current vaccines wouldn’t work, noting they are effective against numerous other variants.

Even though some of the genetic changes in omicron appear worrying, it’s still unclear if they will pose a public health threat. Some previous variants, like the beta variant, initially alarmed scientists but didn’t end up spreading very far.

“We don’t know if this new variant could get a toehold in regions where delta is,” said Peacock of the University of Cambridge. “The jury is out on how well this variant will do where there are other variants circulating.” To date, delta is by far the most predominant form of COVID-19, accounting for more than 99 per cent of sequences submitted to the world’s biggest public database.

Lawrence Young, a virologist at the University of Warwick, described omicron as “the most heavily mutated version of the virus we have seen,” including potentially worrying changes never before seen all in the same virus.

Is It More Contagious?

It’s hard to discern whether it’s more contagious than others, but the evidence suggest the new variant is highly contagious. Tulio de Oliveira directs the Centre for Epidemic Response & Innovation in South Africa. He calls B.1.1.529 a “variant of great concern” and tweeted yesterday that: “B.1.1.529 seems to spread very quick!” noting that the variant now “dominates all infections following a devastating Delta wave in South Africa.” The WHO underscored this concern, writing: “this variant has been detected at faster rates than previous surges in infection, suggesting that this variant may have a growth advantage.”

Why are scientists worried about it?

The variant has more than 30 mutations on its spike protein – the key used by the virus to unlock our body’s cells – more than double the number carried by Delta. Such a dramatic change has raised concerns that the antibodies from previous infections or vaccination may no longer be well matched. Purely based on knowing the list of mutations, scientists anticipate that the virus will be more likely to infect – or reinfect – people who have immunity to earlier variants.

Will existing vaccines work against it?

Scientists are concerned by the number of mutations and the fact some of them have already been linked to an ability to evade existing immune protection. These are theoretical predictions, though, and studies are rapidly being conducted to test how effectively antibodies neutralise the new variant. Real-world data on reinfection rates will also give a clearer indication on the extent of any change in immunity.

Scientists do not expect that the variant will be entirely unrecognisable to existing antibodies, just that current vaccines may give less protection. So a crucial objective remains to increase vaccination rates, including third doses for at-risk groups.

When Will We Know More?

According to Slavitt, the world will have to live with uncertainty for a while: “It will take 2 weeks or so to test in a lab whether the mRNA vaccines are effective,” he tweets, “and if so, how effective they are.”

Travel bans may not help - New Zeakand based virologist Dr Chris Smith

South Africa's Health Minister Joe Phaahla told reporters that the flight bans were "unjustified".

"The reaction of some of the countries, in terms of imposing travel bans, and such measures, are completely against the norms and standards as guided by the World Health Organisation," he said.

The World Health Organization has warned countries not to hastily impose travel restrictions, but many already have.

Dr Smith said a short time after Delta emerged, it was detected in more than 50 countries which meant travel bans weren't much help.

"So actually shutting the borders to one meant that you were basically cutting off your nose despite your face because it just comes in from one of the 50 others and that is exactly what's going to happen here."

It was accepted the virus would continue to spread and mutate, but government restrictions helped to slow it down and buy time.

"It enables us to reinforce vaccination because most people are pretty optimistic that the vaccines will continue to work quite well, it's just a question of maintaining high levels of immunity.

That time also enabled scientists to learn more about the new variant and the threat it could pose.

"Hopefully we will know quite soon if it is a major threat or not and the governments of various countries can make an appropriate decision."