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.

Pope Francis and his predecessor, Pope Emeritus Benedict XVI, have received their first dose of a COVID-19 vaccine, according to Vatican spokesman Matteo Bruni.

"I can confirm that as part of the Vatican City State vaccination program to date, the first dose of the COVID-19 vaccine has been administered to Pope Francis and the Pope Emeritus," Bruni said in a statement Thursday.

Francis, who turned 84 last month and had part of a lung removed when he was younger, reportedly received the shot Wednesday while Benedict, 93, reportedly got it Thursday.

Vatican City, an independent enclave surrounded by Rome that serves as the headquarters of the Roman Catholic Church, launched the immunization campaign on Wednesday, administering doses of a COVID-19 vaccine developed by U.S. pharmaceutical giant Pfizer and its German partner BioNTech.

The tiny city-state has a population of only around 800 people but employs more than 4,000. It's unclear how many doses of the Pfizer/BioNTech vaccine have been procured so far.

Vatican City citizens, along with employees and pensioners, will have the opportunity to receive the vaccine as well as family members who are entitled to use of the city-state's health care system. Priority is being given to health care workers, public safety personnel, the elderly and individuals who are most frequently in contact with the public, according to Bruni.

The vaccination campaign is voluntary and people under the age of 18 are being excluded for the time being, Bruni said.

Since the start of the pandemic, Vatican City has reported at least 27 confirmed cases of COVID-19, according to a real-time count kept by Johns Hopkins University.

ABC News' Phoebe Natanson contributed to this report.