How do we know that Omicron is in Nigeria?
Using a technique known as genomic sequencing, all suspected Omicron test results have been analysed and some people are confirmed to have been infected with the variant,
It is likely there are many more cases of the variant already in the Nigeria, as yet undetected, because it can take some time for this process to be completed.
The dominant variant of coronavirus is still Delta, which is responsible for around 40,000 new cases every day in the UK.
Do lateral flow tests detect Omicron?
Rapid or lateral flow tests, which can be used at home, can't tell you which variant you're infected with – but they are still thought to be able to tell you if you're negative or positive, even with Omicron.
What’s the difference between Omicron and other variants?
The Omicron variant has lots of different mutations that haven't been seen before, and many that have.
A large number of them are on the spike protein of the virus, which is the target of most vaccines, and that's the main concern.
In standard tests, Omicron has what's known as an “S-gene dropout” (which Delta, in most cases, hasn't), and that gives a clue that it could be the new variant.
But not all “S-gene dropouts” will necessarily be omicron – full genomic sequencing is needed to be sure.
What are the symptoms of Omicron?
So far, in South Africa, most people infected are young and their symptoms have been mild.
There is some suggestion that the variant could be causing some slightly different symptoms to Delta – including aches and pains, and no loss of taste or smell – but it's too early to say for certain.
At the moment, the World Health Organisation says there is no evidence that symptoms of Omicron are different to those of other variants.
That means a new cough, a fever and loss of taste or smell are still the main three symptoms to look out for.
Hospitals in South Africa are seeing more young people admitted with more serious symptoms – but many are unvaccinated or have had only one dose.
This suggests that getting two doses and a booster dose is a good way of protecting against disease caused by the new variant, as well as all other variants.
What else do we know about Omicron?
Very little is known about how the variant acts or how much of a threat it could be.
For example, it's not clear if it spreads more easily, if it makes people more unwell than other variants or if protection from vaccines will be lower than previously thought.
But on paper it looks worrying, and that's why governments are acting quickly in case it's bad news.