Omicron is currently infecting 200,000 people a day across the UK, according to modelling from the UK Health Security Agency (UKHSA).
The health secretary said the COVID variant now represents more than 20% of coronavirus cases in England, adding: "The UKHSA estimates that the current number of daily infections are around 200,000."
It's understood that the number can change as the growth changes in the future - but it is the agency's best estimate for Monday 13 December.
Sajid Javid also added that Omicron, which is thought to be much more transmissible than previous variants, represents more than 44% of infections in London, and it is expected to become the dominant variant in the capital "in the next 48 hours".
"There are now 4,713 confirmed cases of Omicron in the UK," Mr Javid told MPs.
Estimated infections are different from confirmed cases, as many are asymptomatic or carry symptoms so mild they are never tested.
Speaking in the House of Commons on Monday, Mr Javid updated MPs on new changes to COVID passports in England.
The changes include:
- People in England will need two jabs and a booster dose to get into large venues, or a negative lateral flow test, as part of their COVID pass - once they have had a reasonable chance of getting a booster
- The COVID pass for international travel will be rolled out to include those from the ages of 12 to 15 years old
"It's vital we remember that hospitalisations and deaths lag infections by around two weeks, so we can expect those numbers to dramatically increase in the days and weeks that lie ahead," he added.
On Sunday night, Boris Johnson announced the booster programme in England would be brought forward, with the aim of getting all adults boosted by the end of December.
Welsh First Minister Mark Drakeford announced on Monday that Wales would be doing the same, as he revealed there are 30 confirmed Omicron cases in the country - but warned it will be the dominant variant "by the end of the month".
On Monday evening the PM said that "more than half a million people booked their booster jab today" branding it an "incredible feat".
"Thank you to everyone who has answered the call - please tell your friends and family to Get Boosted Now," he added.
Mr Javid also said from Tuesday, fully vaccinated contacts of someone who tests positive will be able to take daily lateral flow tests instead of self-isolating.
Comment: Big Pharma rakes it in.
Earlier in the day, the government website suspended orders for lateral flow tests "due to exceptionally high demand". Many pharmacies have also run out of tests, with those that have them experiencing long queues.
However, Mr Javid said: "The UK has sufficient lateral flow tests to see us through the coming weeks.
"If anyone finds they are unable to get a kit online, they should check the website the following day or pop down to their local pharmacy and pick up a kit."
Mr Johnson repeatedly declined to rule out further restrictions ahead of Christmas on Monday, but Mr Javid said there were "no plans that I know of" for additional measures.
Comment: COVID: UK could see 'more stringent measures' in New Year after Christmas mixing, expert says
The health secretary added that two jabs are not enough to prevent symptomatic infection from Omicron, but UKHSA analysis has shown a third dose is 70% effective.
He said more than 40% of adults in the UK have now had a booster, and Saturday saw a record number of boosters given - more than half a million.
With the booster programme now open to all adults and the target for all adults to be boosted being brought forward to the end of this month, Mr Javid said more than 840,000 - the daily jab record - will need to be beaten every day.
He said he was confident that can happen, with more vaccination sites opening, and for longer, as well as thousands of volunteer vaccinators being trained and 42 military planning teams being drafted in to help.
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