Positive tests have exceeded 90,000 for each of the past two days, and ministers have said infections are doubling every two to three days.

Health Secretary Sajid Javid declined to rule out stronger U.K. Covid-19 rules before Christmas after the nation's top health advisers urged greater limits to contain infections they estimate are running in the hundreds of thousands per day.

"It's time to be more cautious: we know this thing is spreading more rapidly," Javid told BBC News on Sunday.

When asked whether he could guarantee a so-called circuit-breaker lockdown wouldn't be imposed within days, he replied: "There are no guarantees in this pandemic. At this point, we just have to keep everything under review."

Sajid Javid can't rule out more restrictions before Christmas

Omicron spreading rapidly in U.S. and could bring punishing wave as soon as January, CDC warns

"There are no guarantees in this pandemic," says the health secretary, "at this point we just have to keep everything under review"

U.K. Covid cases have surged to record levels as the fast-spreading omicron variant takes hold. Positive tests have exceeded 90,000 for each of the past two days, and ministers have said infections are doubling every two to three days.

Minutes released Saturday by the government's Scientific Advisory Group for Emergencies, or SAGE, suggested that without stronger rules, hospitalizations could reach a peak of at least 3,000 a day -- far above current levels. 

Pressure on Johnson

The projections put Prime Minister Boris Johnson in a bind, squeezed between scientific advisers calling for urgent action, and MPs who just last week rebelled in record numbers against far milder Covid rules than SAGE now says are warranted to keep the National Health Service afloat. 

To make matters worse for the prime minister, on Saturday evening, his minister in charge of post-Brexit negotiations, Lord David Frost, quit his post, openly undermining Johnson over both his negotiations with the European Union and his response to the surging pandemic.

"We also need to learn to live with Covid," Frost wrote in his resignation letter to Johnson. "I hope we can get back on track soon and not be tempted by the kind of coercive measures we have seen elsewhere."

The letter showed the kind of pressures being exerted on Johnson by his own party to avoid tougher regulations. Last week, 100 Tory MPs voted against plans to introduce Covid passes as a requirement of entry to venues and large events. The measure was only approved because of support from the opposition Labour Party. 

The "crisis of confidence" in Johnson's leadership from the Tories "is impacting on the government's public health response," Labour's shadow health secretary Wes Streeting told Sky, adding that Javid "looked like a hostage to his own party."

Adding to the pressure on the country's health system, the British Medical Association said almost 50,000 NHS staff could be off sick by Christmas if the government doesn't act.

While stopping short of calling for a fresh lockdown, SAGE said bringing back some of the restrictions used earlier in the year could "substantially reduce" the peak in cases. U.K. papers have been filled with speculation that tighter rules may be introduced right after Christmas.

Omicron replicates 70 times faster than delta in airways, but lung infection appears less severe, study says

Johnson must now decide whether to risk the wrath of his rank-and-file MPs to bring in tougher measures. They're already angry at missteps by the prime minister that started with his botched attempt to prevent Parliament's suspension of his friend, Conservative MP Owen Paterson, over lobbying violations. That culminated in the party's calamitous defeat in a special election on Thursday to replace Paterson -- whose former seat of North Shropshire had been Tory for almost two centuries.

Javid told Sky that the government needs to balance scientific advice with the impact measures such as lockdowns have on society, businesses and children.

He said the U.K. is in a different situation now than earlier in the year because of its vaccination program, with over half of adults having received a booster. 

"If there was a need to take any further action, we would recall parliament and it would have to be a decision for parliament," he said. 

Cabinet Office Minister Steve Barclay will hold talks on Sunday with regional governments in Scotland, Wales and Northern Ireland to discuss how to approach the surge in Covid cases, according to a person familiar with the matter.

Existential Threat

The SAGE document said omicron is spreading fastest in London, where Mayor Sadiq Khan on Saturday declared a "major incident," allowing the city to coordinate emergency services and access government support. Khan on Sunday told BBC News he thinks it's "inevitable" new restrictions will be needed.

"Sooner rather than later we're going to need to look at social distancing, we're going to need to look at household mixing," Khan said. 

Khan said that even absent a formal lockdown, the current wave of the virus is an "existential" threat to businesses in the city center, including hospitality and theaters, as customers stay away in droves. He urged fresh government assistance. "This is as bad as March in 2020," Michelin-starred London chef and restaurateur Michel Roux Jr said on Sky. "What should be our most prosperous month is now turning into a loss."