It is clear that the new Omicron variant of Covid-19 is a major development and it is causing serious concern about the world.

But with round-the-clock scientific work taking place all over the globe to establish just how serious this new strain of the virus is it remains to be seen whether or not it will be a game-changing moment in the pandemic. Check out 10 key things about Omicron here.

With 11 cases already detected in the UK the chief medical officer Dr Frank Atherton has warned it is only a matter of time before a case is picked up here.

Action has so far been swift. International travel rules have changed and all UK nations have adopted advice to roll out the vaccination booster programme to everyone over the age of 18.

Secondary school pupils will revert to wearing masks in the classroom though it remains to be seen if the date of the Christmas break will be brought forward.

Rising numbers of Covid cases in one school, not connected to the Omicron variant, have already forced its temporary closure.

So while the national infection rate in Wales has been dropping it nevertheless remains a testing time – particularly less than four weeks out from Christmas with many people planning grander celebrations after last year's muted festivities.

While the situation is evolving rapidly we sat down with Dr Atherton to establish what we actually know so far about Omicron and just how concerned we should all be about this apparent new chapter in the pandemic.

Is the Omicron variant less deadly than the delta variant?

This is an intriguing area of investigation because there doesn't seem to be a significant number of hospitalisations accompanying the surge in Omicron in southern Africa. However there are also worrying signs that it can reinfect people who have already had Covid.

Dr Atherton said: "What we've seen from southern Africa is very significant evidence that there's a higher transmissibility of this Omicron variant compared with the delta variant. We've seen in those countries as well that the virus seems to be reinfecting people who previously were immune. But you are right to say there is an outstanding question about how virulent it is and how much harm it causes in terms of hospitalisation and deaths.

"Now what I would say is that the population in southern Africa is significantly different. It's a relatively younger population. This wave of Omicron variant is really quite new and we've always seen with every wave we've had of coronavirus that it takes some time for the community transmission to translate into hospital harm. So we just don't know how much harm will accrue on that basis and ministers here are tending to take a precautionary approach and try to make sure that we don't allow this to surge if possible."

This begs the questions that if this variant transmits more but is less deadly than other variants could it out-compete the other Covid viruses?

"Well theoretically it could," said Dr Atherton. "All of these variants have different characteristics and something which was highly transmissible but didn't cause a lot of population harm would be far preferable to something which is highly transmissible and which causes a lot of harm.

"We could think of flu. Flu is very transmissible. It causes harm every year and people die of influenza every year but not in the numbers that we've seen with previous waves of coronavirus.

"So potentially that that could be a more favourable position than we've been we've been in the past. But we can't be complacent really. And we know that there's an equally possible scenario that [Omicron] could be more transmissible and more pathogenic and that would be the thing that we would be most fearful of."

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When are we going to start getting answers to the as-yet unanswered questions about Omicron?

At present scientists all over the world are scrambling to gather as much information on the new variant as they can. Part of this will be testing it in a lab to see if our existing vaccines are effective against it.

Dr Atherton said: "It's it's very difficult to look into the crystal ball on this one at the moment. But there's a couple of things we can do. It will take a couple of weeks probably for the labs in the US and in the UK to culture the virus and to really understand its characteristics and the likelihood that it will escape our immune systems.

"Having said that there is real-world evidence we can look to. So this variant first surfaced, of course, in southern Africa and so watching the pattern of epidemiology there – even though the population is a bit different and the immune status of the population is different – that will give us some clue. Because if we start to see the the variant expanding into older age cohorts, and if we see those older age cohorts coming to harm, that will give us some indication of what's happening here.

"Ultimately we will, of course, be watching very carefully what our hospital hospitalisation rates here in Wales and in the UK are doing. They are on a downward trend at the moment as the delta virus wave hopefully is waning. But if that starts to turn and the rates go up again, and we start to see more harm in our communities, then that would also be a trigger for action."

If the variant is more transmissible could we see the huge spikes in cases we have seen in previous waves?

Dr Atherton said: "It's possible [we will see large spikes] and that depends on how effective the variant is at evading the already-existing immunity in the population.

"So we have a certain degree of immunity from natural infection and we have a certain degree of immunity from vaccination although we know that is probably waning. And what we think we're seeing in southern Africa, which has a different pattern of immunity, because they don't have such high rates of vaccination but they have had very significant rates of natural infection, is that the virus is managing to evade that and reinfect people who have previously had immunity.

"So it is a significant worry that we could see that in Wales. But the other part of the equation is how much harm comes from that. If you have a virus which reinfects people but doesn't cause very much harm then that's something we could probably live with.

"But if you have a virus that reinfects people and we go back into a cycle of very significant harm in terms of people being hospitalised and needing to be treated in ICUs and ultimately dying then we have a real problem on our hands. And that's why we want to buy time so that we can get booster doses into people because that's still one of our most effective lines of defence."

How easily can we tweak our vaccinations to combat the new variant? How long will this take?

This is an important question and the answer is encouraging. WalesOnline spoke to several experts to try and find the answer.

Martin Michaelis, is a professor of molecular medicine at the University of Kent. He said: "Technically this is very easy – almost as simple as changing the tyres on a car. Hence a tailored vaccine can be developed within weeks. However there will be a gap of months until enough vaccine doses are produced to start a large-scale vaccine rollout."

Richard Stanton is a reader in virology in the division of infection and immunity at Cardiff University's School of Medicine. He agreed with this assessment, saying: "Now we know that the current vaccines work well (when they match the variant) tweaking them to match the new variant is fairly straightforward. Some of the vaccine companies have estimated around three months to make a modified vaccine.

"Then we have to decide how the new version of the vaccine will be tested and licensed and it will take time to make enough for widespread use. At the moment we don’t know how long that will take but I’m sure discussions are ongoing at the relevant regulatory boards to make some decisions so approval can happen as quickly as possible."