Vaccines are still "expected" to work against the Omicron variant as several cases are recorded in the UK.

Close contacts of positive Omicron cases are being ordered to isolate for 10 days even if they have been vaccinated under emergency measures that were announced over the weekend.

The first two infections of the new coronavirus variant were identified in Nottingham and Essex.

Dr Jenny Harries, the chief executive of the UK Health Security Agency, acknowledged it was “very likely” that further cases of Omicron would be discovered in the coming days.

But will the vaccines still work against the Omicron variant? Here's what health experts and Government officials have said.

Read similar articles: Booster jab could be extended to all adults in the UK

Will coronavirus vaccines still work against the Omicron variant?

Health minister Edward Argar has reassured people there is "no evidence yet that the vaccine is ineffective" against the Omicron variant.

 “In the current circumstances, we don’t see that that is needed at this point because there is no evidence yet that the vaccine is ineffective against this new variant.”

- Health minister Edward Argar to BBC Radio 4's Today programme

Meanwhile Professor Greg Towers, from the Division of Infection and Immunity at University College London, also reaffirmed that many experts predict current coronavirus vaccines will still work against the Omicron variant.

He told Times Radio: “The expectation is the vaccines will still work and the question is, do they work as well or a little bit less well?

“So the vaccine will still work – we want to know if it’s going to be a little bit less effective.

“And the vaccine companies want to know if they’re going to have to make a new vaccine using this new spike protein from the Omicron, which is relatively straightforward to do and they’ll do that if it’s less effective.”

Asked whether Omicron could produce milder illness, Professor Towers said: “There’s not been really enough cases to be sure about that… but I think that it could be less pathogenic.

“Previous strains, the Alpha and the Delta has been suggested to be slightly more pathogenic. Everything we do in this virus is unprecedented.”

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Professor Anthony Harnden, deputy chair of the JCVI, said that if Omicron “turns out to have a transmission advantage, then it would be sensible to have a new vaccine”.

He added: “The mRNA vaccines, that’s the Pfizer and the Moderna vaccines, are relatively easy to tweak and the pharmaceutical companies that produce those vaccines have indicated that they may be able to get a variant vaccine within 100 days.”

Will booster jabs be used to fight against the Omicron variant?

Millions of adults in the UK are set to be offered the Covid booster vaccine with government advisors considering extending the jab to all adults to limit the spread of the Omicron variant.

A decision from the Joint Committee on Vaccination and Immunisation (JCVI) on expanding the programme and cutting the gap before a third dose could come as early as Monday, November 29.

In the latest coronavirus briefing from the Scottish Government, Nicola Sturgeon said vaccination remains the "most important line of defence".

The Scottish Government is ready to put into operation any updated advice from the JCVI in relation to booster jabs.

Ms Sturgeon said: “We will do that as quickly as is possible.”

The First Minister added: “Vaccines remain our best line of defence and I want to stress at this point, if and it is still an if, the vaccines do prove to be less effective against this new variant, vaccination will still be hugely important – less effective does not mean ineffective.

“If anything the new variant makes it more important not less important to get all doses of the vaccine.”

'Inevitably everybody will be offered a booster'

Professor Anthony Harnden, deputy chair of the JCVI, told BBC Breakfast: “Inevitably everybody will be offered a booster but what we want to do is make sure that it’s done in a sensible order so that those that are most vulnerable for this infection can get boosted and their natural immunity levels can go up.”

He said the JCVI was looking at reducing the interval between second and booster doses and increasing the age range of who is eligible.

He said it was “really important that we get the immunity levels in the population high” in case the Omicron variant was more transmissible or protection from vaccines was reduced.

Other health experts weighed in on the booster jab speculation - including Professor Jeremy Brown, member of the JCVI and professor of respiratory medicine at University College London.

Asked about the six-month gap between boosters, Professor Brown told Times Radio: “The reason for the gap is to make sure that we are vaccinating the best and the most important people first – those that have had the longest period of time (since their first course of vaccine) so their antibody levels have waned at the most.

“And they also happen to be the most susceptible due to their age and underlying clinical condition which makes them much more likely to get severe Covid.

“So the reason for the gap is to ensure that we target the most susceptible people first for a booster vaccination.

“The logic for maybe changing the gap… this variant the Omicron variant is now present in the world, it hasn’t reached the UK in high numbers, and if possible it will be good to boost a lot of people’s antibody levels to high levels to give them the maximum chance of not getting infected with this new variant.

“So that might be a reason for reducing the gap. Between the second dose and the booster dose.

“And so basically vaccinate people ahead of a possible Omicron wave which will be coming at some point.”

Will teenagers aged 12-15 get boosters due to the Omicron variant?

Professor Anthony Harnden, deputy chair of the JCVI, told BBC Breakfast that at the moment, those aged 16 and 17 have a second vaccine dose at 12 weeks, while 12 to 15-year-olds have been recommended a single dose.

He said there was an argument to reduce that dose time to eight weeks and look at whether 12 to 15-year-olds should have a second dose.