The U.S. is forecast to have almost 500,000 COVID-19 deaths by mid-February, incoming CDC Director Dr. Rochelle Walensky said on CBS’ "Face the Nation" Sunday morning.

She added, "That doesn't speak to the tens of thousands of people who are living with a yet uncharacterized syndrome after they've recovered."

Walensky, who was appointed by the Biden administration, believes that 100 million more doses of the vaccine will be available within the next 100 days.

"That is what the president-elect has promised," she said. “It will be a hefty lift, but we have it in us to do that.”

ABC News’ Brian Hartman contributed to this report.

People seeking COVID-19 vaccines in Houston were sent away from Minute Maid Park after appointments were overbooked.

The Houston Health Department announced Saturday that it had run out of vaccines by 6 p.m. after it had administered 5,451 doses at the site, where the line wrapped around the building, ABC Houston station KTRK reported. Several people left without getting vaccinated.

Houston Health Department Stephen Williams said during a press conference Saturday he warned the mayor that there wouldn’t be enough doses to last the week.

The city received “a little” over 30,000 doses, Houston Mayor Sylvester Turner said in a statement.

-ABC News’ Ahmad Hemingway contributed to this report.

Prince William championed the effort of the NHS, the U.K.'s health agency, in delivering the COVID-19 vaccine in a video posted to Kensington Royal's Twitter account Saturday night.

The video included several health care professionals on a Zoom call, along with the Duke of Cambridge, talking about distributing and delivering the vaccine.

"This is because we have a world-leading NHS, this is because we have the right people, the right research and development here," William says in the video.

William also encourages people to get the vaccine when they are eligible, noting his "grandparents" -- Queen Elizabeth and Prince Philip -- got the vaccine already. The palace said last week that Elizabeth, 94, and Philip, 99, had gotten the vaccine.

"My grandparents have had the vaccine and I'm very proud of them for doing that," he says in the video. "So it's really important that everyone gets their vaccine."

Los Angeles County, the hardest hit region in the country right now, announced it has crossed 1 million confirmed cases of COVID-19 on Saturday.

The county has identified 1,003,923 cases since the start of the pandemic -- the first county in the country to cross the mark. Only four states outside of California have met that ignominious total. The county announced 253 new deaths and 14,669 new cases on Saturday.

There are currently 7,597 people hospitalized in LA County with COVID-19 -- down slightly from days earlier when the total crossed 7,900.

Also of concern, the county identified its first case of the so-called U.K. variant on Saturday. The case was discovered in a man who was recently in LA, but has since traveled to Oregon, where he is isolating, the health department said.

"The presence of the U.K. variant in Los Angeles County is troubling, as our healthcare system is already severely strained with more than 7,500 people currently hospitalized," said Dr. Barbara Ferrer, director of public health. "This more contagious variant makes it easier for infections to spread at worksites, at stores, and in our homes."

There had already been 40 cases of the variant, officially called the B.1.1.7 variant, detected in California.

It's just over a week into 2021 and the United States has already seen its worst week on record for both COVID-19 infections and deaths.

In the first 10 days of the month, the country has recorded some 2.35 million COVID-19 cases and more than 28,000 deaths from the disease. That works out to be around 163 Americans diagnosed with COVID-19 every minute, and approximately one American death from the disease reported every 30 seconds, according to an ABC News analysis of data compiled by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

The U.S. has not seen a day with fewer than 100,000 new cases in more than two months, with a record-high average of 243,000 newly confirmed infections every day. In the last week alone, that average of daily cases has increased by approximately 16.3%.

Sunday marked the 41st consecutive day with more than 1,000 fatalities from COVID-19 reported nationwide. The country's average of daily deaths jumped by 21.4% in the last seven days.

Meanwhile, more than 129,000 people are currently hospitalized with COVID-19 across the U.S. -- a number that has hovered around 130,000 for the last several days.

At the current rate, January could surpass December's staggering COVID-19 totals to become the nation's hardest hit month of the pandemic.

ABC News' Brian Hartman and Arielle Mitropoulos contributed to this report.