The United States registered an additional 4,022 deaths from COVID-19 on Wednesday, according to data collected by The COVID Tracking Project, a volunteer-run effort to track the U.S. outbreak.

That marks the second day in a row that the country's daily COVID-19 death toll crossed 4,000, and the third time since Jan. 7, according to The COVID Tracking Project.

The seven-day average of COVID-19 deaths is up by 10% or more in 26 U.S. states as of Wednesday, compared to the previous week, according to The COVID Tracking Project.

The U.S. also confirmed 219,090 new cases of COVID-19 on Wednesday, while 130,383 people remained hospitalized with the disease, according to The COVID Tracking Project.

Mississippi has allotted its entire supply of COVID-19 vaccines and doesn't expect more doses until mid-February, the state health department announced Wednesday.

"Neither the county health department drive-through sites, nor the [University of Mississippi Medical Center] vaccine scheduling website was designed to accommodate the monumental surge we are currently experiencing," the Mississippi State Department of Health said in a statement. "At this time, we have no additional vaccine, and every appointment is tied to an actual vaccination."

New appointments are expected to resume after an anticipated vaccine resupply in mid-February, the department said.

On Tuesday, the state opened vaccine eligibility to people ages 65 and older and those with certain chronic health conditions, which led to an influx of calls to the state's COVID-19 hotline, officials said. Previously, vaccinations were prioritized for health care workers, long-term care residents and those over the age of 75.

"We decided to open vaccines to many more people. We knew it would cause a rush, but believe it is more fair than having government arbitrarily limit access," Gov. Tate Reeves said on Twitter Wednesday evening.

As of Tuesday, the state had administered 62,744 vaccinations over the last four weeks, Reeves said during a press briefing.

ABC News' Will Gretsky contributed to this report.

Disneyland Resort in Anaheim, California, opened as a mass COVID-19 vaccination site Wednesday.

About 3,000 people were expected to receive the vaccine on the first day, with about an hour-and-a-half wait time, county officials said. The site ultimately should be able to vaccinate over 7,000 people a day, Orange County First District Chairman Andrew Do said at a press briefing.

Vaccinations are by appointment only. Those without an appointment and proper identification will be turned away, the Orange County Health Care Agency warned repeatedly on Twitter Wednesday.

Over 10,000 people signed up for a slot within two hours of online registration opening on Tuesday, officials said. Disneyland has been closed to parkgoers since last spring.

Other mass vaccination sites are slated to open in the hard-hit state, including Dodger Stadium in Los Angeles and Cal Expo in Sacramento. Petco Park in San Diego also opened earlier this week as a vaccination site.

People in Phase 1A -- health care workers and long-term care residents -- currently have the highest priority to receive vaccines in California.

On Wednesday, the state announced that people 65 and older are also now eligible, in an effort to help speed up vaccine distribution.

The Walt Disney Co. is the parent company of ABC News.

ABC News Abigail Shalawylo contributed to this report.

COVID-19 cases continue to be significantly lower in younger kids, even as some went back to school in-person, according to a new report from the Centers for Disease Control and Prevention.

The incidence of COVID-19 in children, particularly those ages 0 to 10, has been lower than that of young adults and adults throughout the entire second half of 2020, according to the CDC. The incidence of COVID-19 cases in kids was higher as the age increased.

While older teenagers and young adults saw a surge of cases near the beginning of the school year, this was not seen in younger kids, "suggesting that young adults might contribute more to community transmission than do younger children," the report said.

Children also had significantly lower rates of hospitalizations, intensive care unit stays and death than adults, the study found.

Fewer COVID-19 tests are performed on children, so the actual incidence may be higher than the data that's available.

Teacher and school employee transmission risk also were not included in the data.

The CDC continues to recommend strict mitigation strategies to prevent transmission in schools that are in-person.

-ABC News' Dr. Rose Marie Leslie

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.