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

Uganda reopened its schools to students on Monday after nearly two years, ending the world's longest school closure due to the coronavirus pandemic.

Schools across the East African nation of 44 million people have been fully or partially closed since March 2020, when the pandemic began. The closures affected more than 10 million learners, according to data from the United Nations Educational, Scientific and Cultural Organization (UNESCO).

Save the Children welcomed the reopening of Uganda's schools but warned that "lost learning may lead to high dropout rates in the coming weeks without urgent action."

The London-based charity revealed in a report last November that up to one in five children in low-income countries, including Uganda, had dropped out of school due to rising poverty, child marriage and child labor, which have been exacerbated by the pandemic. In a statement Monday, Save the Children warned of "a 'second wave' of dropouts as returning students who have fallen behind in their learning fear they have no chance of catching up."

To tackle the potential crisis in Uganda, Save the Children has launched "Catch-up Clubs," which assess children and teaches them at the required level to help them regain literacy and other learning, with child protection support and cash assistance for families struggling to send them to school.

"As schools begin to reopen across the country, it is critical that all girls and boys have access to the support they need to successfully return to the classroom," Edison Nsubuga, head of education at Save the Children in Uganda, said in a statement Monday. "Many children have fallen behind in school as a result of the COVID-19 pandemic. Children who are behind in their learning are less likely to unlock their potential as adults. However, when children receive the learning boost they need and have access to quality education, they can reach their full potential."