A new strain of the coronavirus is causing concern - but how is it different to what we have seen before?
Doctors and scientists are working to learn more about the Omicron variant, which was first identified in South Africa.
In response to the discovery of the new variant, Prime Minister Boris Johnson announced the reintroduction of some restrictions in public.
People are now required to wear masks in shops and on public transport.
Contacts of those with the Omicron variant are also being required to isolate for 10 days.
PCR tests are effective in identifying the strain and there is an expected announcement that the booster jab will become available to all UK adults.
As well as this, any person arriving in the UK must take a PCR test on their second day and isolate until they have a negative result.
Officials said this morning that six new cases were confirmed in Scotland and the UK announced its first three cases of the new mutant virus strain over the weekend.
So what is the Omicron variant?
What is the Omicron Covid-19 variant?
Omicron is a mutated strain of the coronavirus.
It is feared that compared to other strains, Omicron is more resistant to vaccines and more easily transmitted, but this has not been confirmed.
Viruses are adaptable and this means that they develop over time due to genetic mutations also known as 'copying errors'.
Our immune systems are trained to recognise certain viruses and will produce antibodies in order to fight against them.
Vaccines help to build up antibodies to protect us from specific viruses.
Mutations look slightly different to our antibodies and the part they use to attack other cells can change.
This makes mutations harder for our antibodies to fight.
The Omicron variant is shaped differently to previous strains, making it difficult for our immune system to attack.
It is reported that the general symptoms of the Omicron variant generally affect people with slightly different symptoms than the Delta variant.
How is Omicron different to the Delta variant?
A doctor in South Africa explained that the Omicron "clinical picture doesn't fit Delta."
Chair of the South African Medical Association Dr Angelique Coetzee, told AFP: "We have seen a lot of Delta patients during the third wave.
"And this [Omicron] doesn't fit in the clinical picture. Most of them are seeing very, very mild symptoms and none of them so far have admitted patients to surgeries."
She said that symptoms of Omicron may be more likely to be extreme tiredness, a scratchy throat and mild muscle ache.
As another general expectation, people are more unlikely to experience a loss of taste or smell.
What does Omicron mean?
Like other variants, Omicron has been named by the World Health Organisation after a letter in the Greek alphabet.
The first 12 letters of the alphabet have already been used to name different strains, which is why names such as 'Alpha', 'Gamma' and 'Delta' may sound familiar.
Other variants have not been known to be as strong or effective, so are less famous.
The next letter, after the 'Mu variant', was expected to be named after the letter 'Nu'.
However, Nu and the following letter 'Xi' were skipped and the new variant is named after the next letter, 'Omicron'.
It has been reported that this was done to avoid confusion and for political reasons.
Nu may have sounded like 'new variant', which could have been confusing for people and Xi was avoided due to President Xi Jinping, current leader of the ruling Chinese Communist Party.
