Face masks are once again required in indoor public spaces in England under the measures British Prime Minister Boris Johnson announced this week to slow the spread of the new omicron virus variant. Vaccination passes will be needed for nightclubs and large events starting next week, and residents will be told to work from home, if possible.

The emergence of omicron, which is spreading quickly in Britain, has shaken the government’s hopes that vaccinations would be enough to keep the virus in check. British scientists and officials say omicron spreads more quickly than the currently dominant delta variant and likely is more resistant to current vaccines. It is not yet clear whether it causes more severe, or milder, cases of COVID-19.

Along with the new restrictions, the British government is offering everyone 18 and up a third booster dose of vaccine to try to slow the spread of the virus.

Britain's Prime Minister Boris Johnson

Britain's Prime Minister Boris Johnson leaves 10 Downing Street for the House of Commons for the weekly Prime Minister's Questions in London, Wednesday, Jan. 27, 2021.  (AP Photo/Alastair Grant, File)

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The return of restrictions is unwelcome for many, and revelations of apparent rule-breaking by government officials during tough lockdowns last winter have heightened opposition to the new measures.

The government has asked Britain’s most senior civil servant to investigate several gatherings, including a Dec. 18, 2020, event at the prime minister’s 10 Downing St. offices, where staff reportedly enjoyed wine, food, games and a festive gift exchange at a time when pandemic regulations banned most social gatherings.

Multiple media outlets reported Friday that one of Johnson’s most senior advisers, Director of Communications Jack Doyle, attended the Dec. 18 party and gave awards to staff members. At the time, he was the deputy communications director.

Britain's Prime Minister Boris Johnson visits the National Express depot in Coventry, central England, Monday March 15, 2021. (Steve Parsons/Pool via AP)

Britain's Prime Minister Boris Johnson visits the National Express depot in Coventry, central England, Monday March 15, 2021. (Steve Parsons/Pool via AP)

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In his current role, Doyle has directed the government’s public statements about the party allegations. For several days, Johnson's office denied a party had taken place and insisted rules had been followed at all times.

That claim unraveled when a leaked video showed senior staff members joking about the alleged party. The most senior official in the video, Allegra Stratton, apologized and resigned on Wednesday.

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"It’s been a difficult week for the government," Paul Scully, the U.K.'s small business minister, said Friday, adding that the investigation needed to "get to the bottom" of the allegations.

"We want to see beyond doubt that there were no rules broken, which is what the assurances have been to the prime minister, and that’s what I’ve heard," Scully told the BBC. "I wasn’t there. I don’t know."

The Christmas party claims are the latest in a string of allegations of rule-breaking and ethics violations by Johnson and government officials. On Thursday, Britain’s electoral watchdog fined the prime minister's Conservative Party 17,800 pounds ($23,500) for failing to keep a proper record of money from a donor that was used to refurbish Johnson’s official residence.

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Wes Streeting, health spokesman for the opposition Labour Party, said the stream of allegations undermined trust in the government during a public health crisis.

Streeting blamed Johnson, saying "it’s his untrustworthy nature, his disorganization, his dishonesty, which is undermining trust in public health measures."

"Boris Johnson’s character and behavior starts to undermine a whole series of things: the system of standards in Parliament, the way the law is applied in the country and, crucially, whether the government can get its message across about public health at a critical time," Streeting said.