Despite a backlog in data on COVID-19 cases and deaths over the holiday weekend, the United States still marked a record level of coronavirus-related hospitalizations, according to data collected by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

The data shows there were 128,120 people hospitalized across the country on Monday.

The COVID Tracking Project warned that data on testing, cases and deaths has been affected by the holidays.

"Hospitalization data remains the most stable metric despite the reporting disruptions. The 7-day average is now over 125k," the group wrote on Twitter Monday.

The COVID Tracking Project also noted that the seven-day average for COVID-19 deaths is increasing in 30 U.S. states.

"We expect the daily death numbers to increase significantly once the reporting trends stabilize post-holidays, in part due to backlogs," the group tweeted.

Health officials in Los Angeles County gave a dire warning to residents on Monday, particularly to those who are protesting mask mandates and other coronavirus-related rules, saying the situation is bound to get worse in the coming weeks.

The county has reported a total of more than 800,000 confirmed COVID-19 cases, half of which were marked in December, according to the Los Angeles County Department of Public Health.

About 7,697 people are currently hospitalized with COVID-19, and 10,850 deaths from the disease have been registered in the county, according to the health officials.

Dr. Barbara Ferrer, the director of the Los Angeles County Department of Public Health, warned that hospitalizations could rise to 9,500 in two weeks.

"We're likely to experience the worst conditions in January that we faced the entire pandemic and that's hard to imagine," Ferrer said at a press conference Monday.

Ferrer and other officials spoke out against recent anti-mask protests held in the county.

"This isn't just about you. The facts are the facts, and they are grounded in science," said Dr. Christina Ghaly, director for the Los Angeles County Department of Health Service.

"Wearing a mask is not a statement about how you feel about your own health and your invulnerability," she added. "It's primarily a statement about how committed you are to protecting the lives and the health of those around you."

-ABC News' Matthew Fuhrman and Abigail Shalawylo

The University of California, San Diego has installed vending machines on campus where students and staff can pick up self-administered COVID-19 test kits.

To use the kits, which are free, test takers use the swab outdoors and return the vile within 72 hours, for results in less than two days.

Starting Jan. 2, on-campus students are required to get weekly tests, according to the university.

A new variant of the novel coronavirus that was first identified in the United Kingdom has been detected in New York state, Gov. Andrew Cuomo announced Monday.

The patient is a man in Saratoga Country in his 60s, who had not traveled recently, suggesting community spread of variant. The patient was affiliated with a jewelry store, N. Fox Jewelers, where three other people have also tested positive for COVID-19, although it is not yet known if they have the same virus variant. Anyone who visited the store between Dec. 18 and 24 is being asked to contact the state and get a test immediately.

"From a public health point of view, it’s about contact tracing," Cuomo said. “We have to make sure we are doing everything we can do to effective contact tracing of this case."

Cases of the new variant have also been detected in Colorado, California and Florida.

-ABC News' Aaron Katersky contributed to this report.

The United Kingdom saw another day of rising coronavirus cases, deaths and hospitalizations, according to the British government.

The nation recorded 54,940 new cases Sunday, bringing the total number of cases to 3,072,349, the health data showed. The seven-day average for new cases rose from 21,698 on Dec. 10 to 61,106 on Jan. 1, the British government said.

The U.K. saw 563 new COVID-19-related fatalities Sunday, according to the health data. The country has 81,431 total deaths since the start of the pandemic, the government said.

There are currently 32,294 people hospitalized in Britain. The seven-day average for new hospital admissions rose from 1,728 on Dec. 10 to 3,345 on Jan. 1, officials said.