Today is the last day you can test positive for COVID and not isolate on Christmas Day

Today is the last day that people can test positive for coronavirus and not have to self-isolate on Christmas Day.

The race is on to halt the spread of the Omicron variant of COVID-19, which is set to become the UK’s dominant strain.

The government has already announced Plan B measures and a ramping up of the booster jabs programme in an effort to fight the variant.

However, the UK Health Security Agency (UKHSA) estimates that there are up to 200,000 new COVID-19 infections every day, with Omicron accounting for 20%.

Anyone who has a positive result from a rapid lateral flow test, or who develops one of the official COVID-19 symptoms – either a new continuous cough, a high temperature, or a loss of or change in sense of taste or smell – should self-isolate and take a PCR test to verify the result.

Watch: Boris Johnson refuses to rule out extra COVID measures before Christmas

Read more: Will there be more COVID restrictions before Christmas?

If the PCR test comes back as positive, they must self-isolate for 10 days from the day they took the positive rapid lateral flow test or developed symptoms.

If that start date is Tuesday, then they would have to self-isolate up to and including Christmas Eve.

Anyone who tests positive from Wednesday will have to self-isolate on Christmas Day.

PCR tests were temporarily unavailable across the whole of England on Tuesday due to "exceptionally high demand", officials said.

Twice on Tuesday, the government website said there were no slots available for PCR tests at walk-in and drive-in test sites across every region of England, before making more slots available.

It comes as problems ordering rapid lateral flow tests enter their second day, as new guidance came into force for coronavirus close contacts.

Double jabbed people are now being asked to take a lateral flow test every day for seven days if they come into contact with someone with COVID-19.

Lateral flow tests are unavailable to be ordered via the government website, although it is understood that a number were available in the early hours of Tuesday.

A message on the site says there are no home delivery slots available for the tests, although they can still be collected from pharmacies.

Ministers have insisted there is no issue over supply, but rather there are constraints on the delivery system for the tests, as they encouraged people to pick up testing kits from their local pharmacies.

Boris Johnson issued an appeal on Monday to members of the public to step forward to assist the booster jab programme.

He said “tens of thousands” of volunteers were needed as the vaccination programme is ramped up.

Read more: GPs say they were given 'no notice' of booster drive

They range from stewards to organise and manage the queues to trained vaccinators to administer the jabs.

He said: “As part of our Get Boosted Now vaccination drive we need to increase our jabbing capacity to unprecedented levels.

“But to achieve something on this scale, we need your help.

“So today I’m issuing a call for volunteers to join our national mission to get jabs in arms.

“We need tens of thousands of people to help out, everyone from trained vaccinators to stewards.

“Many thousands have already given their time but we need you to come forward again, to work alongside our brilliant GPs, doctors, nurses and pharmacists, to deliver jabs and save lives.

“So please come forward if you can.”

There are almost 3,000 vaccine sites across the country, staffed by more than 90,000 volunteers.

Watch: Health secretary confirms rapid increase of Omicron infections