The U.S. government is buying 600,000 more doses of sotrovimab, the only the monoclonal antibody treatment expected to hold up against omicron, according to the drug makers, GlaxoSmithKline and Vir Biotechnology.

These doses are set to be delivered to the government over the next two months, the drug makers said.

This brings total sotrovimab doses purchased by the federal government to approximately 1 million.

Short supply of sotrovimab has been a growing concern for the White House as omicron spreads.

Until recently the government had not invested in buying bulk stock of sotrovimab, as it has with other monoclonal treatments. The government spent billions buying Regeneron and Eli Lilly's products to ensure there would be enough supply, but both of those may not hold up against omicron.

-ABC News' Sasha Pezenik

Florida reported 126,704 new COVID-19 cases this weekend, ABC Miami affiliate WPLG reported, citing CDC data.

Orlando opened a new testing site Monday at Camping World Stadium.

About 3,000 United Airlines workers currently have COVID-19, though none are in the hospital, the airline said.

On one recent day, one-third of all United Airlines employees at Newark Airport called in sick, the airline said.

United CEO Scott Kirby said the airline is cutting its near-term flight schedule to ensure they have enough staffing.

Kirby added that, prior to the vaccine requirement, United had one employee die each week from COVID-19.

-ABC News' Sam Sweeney

Some 20 million people across three Chinese cities are now under lockdown due to COVID-19 outbreaks.

Anyang, home to 5.5 million people, was the latest city to lock down its residents after discovering two cases of the fast-spreading omicron variant. Another 13 million people are under lock down in Xi'ian and 1.1 million in Yuzhou, with both cities still battling the highly contagious delta variant. Neither has reported any cases of omicron.

Meanwhile, restrictions have been imposed in the port city of Tianjin, about 80 miles southeast of Beijing, which is to host the 2022 Winter Olympics next month. The city's 14 million people are being tested for COVID-19 after two locally transmitted cases of omicron were detected over the weekend -- the first for mainland China.

-ABC News' Karson Yiu

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."