British Prime Minister Boris Johnson apologized Wednesday for attending a party during England's strict lockdown in 2020.

It was the first time that Johnson acknowledged he went to a garden party at his official residence and office on London's Downing Street in May 2020. He is facing growing anger and calls for his resignation over claims he and his staff flouted COVID-19 restrictions by holding a "bring your own booze" party. At the time, Johnson's government had imposed restrictions barring people in England from meeting more than one individual outside their household.

During the weekly Prime Minister’s Questions session in the House of Commons in London on Wednesday, Johnson said he had considered the garden party to be a work event to thank his staff for their efforts during the pandemic.

"I want to apologize," Johnson told lawmakers. "With hindsight, I should have sent everyone back inside."

The prime minister urged people to await "the full conclusion" of an investigation by senior civil servant Sue Gray into several alleged parties by government staff. Gray will report her findings by the end of the month.

Opposition Labour Party leader Keir Starmer said Johnson's defense was "the pathetic spectacle of a man who has run out of road" and demanded he "do the decent thing and resign."

The prime minister declined to resign and didn't explicitly admit that he had broken any rules, but said he understood "the rage."

"I know that millions of people across this country have made extraordinary sacrifices over the past 18 months," he added. "I understand the anger, the rage that they feel at the thought that people in Downing Street were not following those rules."

-ABC News' Guy Davies, Ian Pannell and Joseph Simonetti

Russian officials are warning that an omicron-fueled wave of COVID-19 infections will soon hit, amid fears about how deadly a surge of the highly contagious variant -- even if milder -- might be in a country with a low vaccination rate.

Russian Deputy Prime Minister Tatiana Golikova, who is overseeing the COVID-19 response, and Moscow Mayor Sergey Sobyanin said Wednesday that the situation could be "more critical" than previous waves of infections in Russia -- a worrying prospect since earlier waves led to a high number of deaths.

Russia has reported more than 312,000 fatalities from COVID-19 since the start of the pandemic, according to data compiled by Johns Hopkins University. However, the country registered just under 1 million excess deaths in 2021.

The Russian government has said the country will soon see six-figure daily cases. Less than 50% of Russians are fully vaccinated against COVID-19, amid widespread reluctance across the nation.

Russian President Vladimir Putin, who has largely tried to downplay the scale of his country's COVID-19 outbreak, warned Wednesday of the imminent increase in infections. Putin said Russia is "on the threshold of possible new outbreaks."

Meanwhile, Russian Health Minister Mikhail Murashko said the country is at a "turning point," which will decide how bad the wave will be. Russian authorities are calling for people to take precautions and observe social distancing measures. However, there are relatively few restrictions in most parts of the country.

Denis Logunov, deputy director of Russia's Gamaleya National Center of Epidemiology and Microbiology, said Tuesday that the nationwide number of omicron cases is expected to rise considerably in late January and early February. The World Health Organization's regional director for Europe, Dr. Hans Kluge, also warned Tuesday that omicron is expected to infect more than half of Europe's population within the next two months.

-ABC News' Patrick Reevell

As U.S. President Joe Biden vows to keep all schools safely open for full-time in-person learning amid the pandemic, his administration announced Wednesday that it will provide schools with an additional 10 million COVID-19 tests per month.

The federal government will send 5 million more rapid tests and 5 million more lab-based PCR tests to schools nationwide each month, at no cost. The rapid tests will be delivered starting later this month, while the PCR tests will be available immediately. The additional tests every month will allow the country's schools to "more than double the volume of testing that took place in schools across the nation in November," according to a fact sheet from the White House.

Moreover, as the Biden administration continues to surge testing sites to hard-hit and high-risk communities, the federal government will also "consider how these sites can support the safe operations of K-12 schools," the White House said.

The U.S. Department of Education and the Centers for Disease Control and Prevention will also help connect schools with testing providers so they can use money allocated to them last year through the $1.9-trillion COVID-19 stimulus package. Later this week, the CDC will provide new training, resources and materials to help schools implement "test-to-stay" policies, according to the White House.

-ABC News' Ben Gittleson

West Virginia Gov. Jim Justice announced Tuesday evening that he tested positive for COVID-19 and is experiencing moderate symptoms.

Justice, 70, who is fully vaccinated against COVID-19 and has received a booster shot, said he has started a course of monoclonal antibody treatment, as recommended by his physicians. Everyone who has been in close contact with the governor over the past few days is being notified. His wife, Cathy Justice, tested negative for the virus on Tuesday evening, according to a press release from the governor's office.

The governor was scheduled to deliver his State of the State address that night but was forced to do so via a written statement to the West Virginia Legislature instead.

"I feel extremely unwell at this point, and I have no choice but to postpone my State of the State address to the Legislature," Justice said in a statement Tuesday evening. "I woke up this morning with congestion and a cough. A little while later, I developed a headache and fever, so I decided to get tested right away."

"The rapid test that I took came back negative, but by the late afternoon, my symptoms were still getting much worse," he continued. "My blood pressure and heart rate were extremely elevated, and I had a high fever. Finally, my PCR test results this evening confirmed I was positive. Because of all this, I began receiving my antibody treatment and I hope this will lessen these symptoms."

The United Kingdom has launched a new advertising campaign that urges pregnant women who have not yet received a COVID-19 vaccine or booster shot to do so as soon as possible.

Testimonies of pregnant women who have had the shots will be played out in ads across U.K. radio stations and on social media starting Monday. The new campaign urges pregnant women "don't wait to take the vaccine" and highlights the risks of COVID-19 to both mother and baby as well as the benefits of getting vaccinated, according to a press release from the U.K. Department of Health and Social Care.

The press release cited the latest data from the U.K. Health Security Agency that suggests COVID-19 vaccination is safe for pregnant women and provides strong protection against the virus for both mother and baby. The press release also cited data from the U.K. Obstetric Surveillance System that shows more than 96% of pregnant women hospitalized with COVID-19 symptoms between May and October 2021 were unvaccinated, and a third of them required respiratory support. Around one in five women who are hospitalized with COVID-19 need to be delivered preterm to help them recover, and one in five of their babies need care in the neonatal unit.

"Getting a COVID-19 vaccine is one of the most important things a pregnant woman can do this year to keep herself and her baby as safe from this virus as possible," Lucy Chappell, chief scientific adviser to the U.K. Department of Health and Social Care, said in a statement Monday. "We have extensive evidence now to show that the vaccines are safe and that the risks posed by COVID-19 are far greater."