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 CDC says it plans to update its mask guidance to “best reflect the multiple options available to people and the different levels of protection they provide.”

The CDC did not say when its guidance will be updated. In the meantime, the CDC said in a statement, “any mask is better than no mask, and we encourage Americans to wear a well-fitting mask to prevent the spread of COVID-19.”

Since the arrival of omicron, health experts have urged Americans to upgrade their cloth masks to an N95 or KN95 because the new variant is so highly transmissible. But these higher-grade masks are costly and hard to find.

Prior to omicron, CDC director Rochelle Walensky resisted suggesting N95 masks for the average American because the CDC didn’t want to discourage people from wearing any mask.

Dawn O’Connell, a top official at the Health and Human Services Department, said Tuesday that the Biden administration plans to increase production of N95s. There are already 737 million N95 masks in the strategic national stockpile available for medical workers.

-ABC News' Anne Flaherty