Downing Street said it was ‘too early to draw conclusions’ but early signs show the new strain spreads more quickly than the Delta variant

Boris Johnson has warned the Cabinet that early signs show the new Omicron variant is more transmissible than the Delta variant.

Downing Street said ministers did not discuss introducing Plan B measures – but said the Government could move “swiftly” if it needed impose new restrictions.

The Prime Minister is planning to make a decision next week on whether further Covid measures are needed once experts have provided more data on the new variant.

Describing the Cabinet meeting on Tuesday, the PM’s official spokesman said “The Prime Minister said it was too early to draw conclusions on the characteristics of Omicron but that early indications were that it was more transmissible than Delta.

“Further measures were introduced this week to help slow transmission and further seeding of the variant, and the Prime Minister reiterated that booster vaccines remain our best defence against new and existing variants, with the NHS on course to meet the target of offering a booster to all adults by the end of January.”

It comes after Health Secretary Sajid Javid told MPs that the variant was now spreading in the community, rather than just linked to international travel.

Downing Street said it is still unclear how severe the disease caused by Omicron is or the impact vaccines have on it.

The PM’s spokesman said: “At this stage it is too early to tell, it remains the case that we don’t have that data through.”

He acknowledged that how severe the disease is will impact how much damage will be caused by the feared increased transmissibility of the strain.

“Depending on the level of severity, depends on what knock-on impact that increase in transmissibility adds,” he said.

“We do have further measures already set out through Plan B, which we can move to should they be required, it’s too early to say at this stage and we will continue to study the data.

“We are able to move relatively swiftly.”

The Government’s winter Covid blueprint includes a list of plan B measures – such as masks, working from home and vaccine passports – which can be brought in if the situation worsens.

Ministers have resisted imposing plan B so far but the emergence of the new Omicron variant has caused concern in Government.

Masks have been made mandatory in shops and on public transport, while tougher testing rules have been imposed for foreign travel.

All arrivals from abroad must now take a Covid test two days before travelling, as well as a PCR test when they get to the UK.

Travellers must isolate until they get their result, even if they are double jabbed.

Isolation rules have also been tightened for any contacts of known Omicron cases.

People now have to stay at home for 10 days regardless of vaccination status.

Mr Johnson is expected to make an announcement to MPs on whether to change Covid restrictions in the final week before Parliament breaks up on December 16.