It is feared there could be as many as 1,000 Omicron cases in the UK already as the latest variant is expected to take hold across the country.

Despite official figures showing just 246 recorded cases, Professor Paul Hunter, from the school of medicine at the University of East Anglia, said it “is spreading rather more quickly than the Delta variant”.

The professor told BBC Breakfast it was not clear how evidence from South Africa would translate to the UK as we have a highly vaccinated population.

He added: “How it’s likely to spread in the UK still uncertain, but I think the early signs are that it will probably spread quite quickly and probably start out-competing Delta and become the dominant variant probably within the next weeks or a month or so at least.”

But Omicron is not the first variant to hit the UK, with Delta accounting for almost all cases of the virus up until now.

In fact, some 17 different variants have been registered across the country, with some having little impact, while others – including Omicron – have been cause for concern, according to experts.

Variants are being investigated and tracked as people test positive for them and figures are published on the government’s website which show the amount of new cases of the variants since the last update, and the total so far.

Here are the full list of Covid variants of concern – kept under closest watch – and how many cases there have been so far.

Omicron

Omicron is the name given to the Covid variant B.1.1.529. It was named by the World Health Organisation, which assigns variants of concern a Greek letter.

It was first identified in Botswana on November 11 and linked to a surge in case numbers in the Gauteng province of South Africa.

Omicron has 35 mutations on its spike protein – which allows the virus to unlock our body’s cells. It is more than double the number carried by the dominant Delta variant.

Scientists believe the variant is highly likely to be more transmissible and has features capable of evading the vaccine antibodies. But whether catching it would lead to more severe illness will not be known for weeks.

But the doctor who discovered the Omicron variant said the UK was “panicking unnecessarily” and that the symptoms are “extremely mild”.

Official figures show 246 recorded cases in the UK but experts fear the true figure may be closer to 1,000.

Alpha

This variant was first detected in the UK and was first sequenced in the UK in September 2020.

As of September, in the UK, a total of 277,588 people had contracted the Alpha variant, with 226,855 of the total cases being recorded in England. It has so far spread to over 50 countries.

The N501Y mutation, seen in the Alpha variant may help the virus spread more easily.

Beta

So far, data up to August 25 shoes there has been 1,093 cases of the Beta variant in the UK.

England accounts for 979 of those cases, Northern Ireland, 9, Scotland, 62, and Wales, 43.

The Beta variant was first identified in South Africa but has been detected in at least 20 other countries. Beta also shares the N501Y mutation, like the Alpha variant, meaning the virus spreads more easily.

Beta also has a key mutation, called E484K that could help the virus sidestep some of the body’s immune defences.

Delta

The most dominant of the variants listed, Delta swept the country this summer, making case numbers rise.

It was first discovered in April 2021 and since then has become the dominant strain of the virus in the UK.

There is no evidence that the Delta variant causes more serious illness. Delta has some undergone some changes to their spike protein, the part of the virus that attaches to human cells.

It means it could spread more easily, although there is no evidence to show it might make current vaccines less effective.

Analysis by Public Health England found two doses of either the Pfizer or AstraZeneca vaccines was more than 90 per cent more effective against hospitalisations for Covid-19 caused by the Delta variant.

A single dose was less effective at preventing illness from Delta, compared to how well it worked against Alpha.

VOC-21FEB-02

This variant was first detected in the UK in December 2020 and there has so far been just 46 cases in total in the UK, with England accounting for 45 cases and Northern Ireland for one, as of September.

Gamma

The Gamma variant was first detected in Japan in travellers from Brazil in January 2021 and was first detected in the UK in February this year.

As of September, there has been a total of 272 cases detected in the UK. All but two cases were recorded in England.

Wales recorded two cases.

The Gamma variant also shares the mutation, N501Y which makes the virus better at infecting cells and spreading.

It also has the E484K mutation that could help the virus sidestep some of the body’s immune defences.

Kappa

The Kappa variant has seen a total of 494 cases in the UK, as of September.

It was first detected in India.

England has recorded 448 cases of this variant, Northern Ireland, four, Scotland, 27, and Wales, 15.

FUN – 21APR-03

This variant was also first detected in India. It is responsible for 16 total cases in the UK, 13 of which were recorded in England.

Little is known about this rare variant.

HAPPY -21FEB-01

Seventy-nine cases have been recorded in total in the UK, all were recorded in England as of September.

Again, little is known about this mutation – but case numbers are thankfully small.

And

The Eta variant was first detected in the UK in December last year.

A total of 497 cases have been recorded in the UK as of September, with 445 of them in England.

Northern Ireland recorded a total of two cases, Scotland, 40 and Wales, 10.

It has been detected in over 23 countries.

VUI-21FEB-04

This variant is responsible for a UK total of 358 cases by September. 302 of those cases were recorded in England, 45 of them were recorded in Northern Ireland and 11 of them were recorded in Scotland.

It was first detected in the UK and declared a VUI in February this year. It also shares the E484k mutation that could help the virus sidestep some of the body’s immune defences.

Zeta

The Zeta variant was first detected in Brazil and was first sequenced in the UK in November last year.

The UK has recorded a total of 60 cases of this variant as of September.

England has recorded 54 cases, Scotland, five and Wales, one.

Theta

Ten cases of this variant have been detected in the UK as of September, with seven in England and three in Scotland.

It was originally detected in the Philippines and was declared a VUI in March this year after two cases linked to travel tested positive in the UK. It contains the mutations E484k and N501Y.

HAPPY-21MAY-01

This variant was one that was found much later than the earlier ones. It was first detected in the UK in May this year but England has already recorded the UK’s total of cases for it, 185.

It was first detected in Yorkshire and the Humber.

HAPPY-21MAY-02

This variant was first detected in Thailand in travellers that had gone there from Egypt.

153 cases have been detected in the UK, with 142 of them being detected in England, three in Nothern Ireland, four in Scotland and four in Wales, as of September.

The variant is based on an “unusual mutation profile” and increased importation from a widening international area.

Lambda

There is a total of eight cases of the Lambda variant in the UK, all of which were detected in England as of September.

It was first detected in Peru in August 2020. All of England’s cases have been linked to overseas travel.

FUN-21JUL-01

This variant has a total of 48 cases recorded in the UK, with 44 recorded in England, one in Northern Ireland, two in Scotland and one in Wales as of September.

It was escalated to a VUI on July 21 this year. There is currently no evidence that it causes more severe disease or renders the vaccines currently deployed any less effective.