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

Weeks after video emerged of mostly maskless partygoers at U.S. President Donald Trump's Mar-a-Lago Club in Palm Beach, county officials are cracking down.

Palm Beach County sent a letter this week, acquired by ABC News, warning the club and saying officials had met with representatives from the club about violations. Masks are mandatory in the county in all businesses or establishments, and anywhere in public social distancing cannot be maintained. The mandate is currently in place through Jan. 20 -- the same day the county's most famous resident will be exiting the White House.

"Thank you for meeting with us last week to discuss the concerning allegations regarding the Mar a Lago New Year's Eve party and lack of facial coverings being worn during evening activities," the county wrote in the letter addressed to Bernd Lembcke, executive vice president and managing director of Mar-a-Lago Club.

"We recount that you provided masks for all party goers who attended the party and that you provided additional masks for those that walked from the reception area to the main dining ballroom," the letter continued. "Although you provided these important steps, it seemed that based on the video evidence, there was a breakdown in enforcement of the mask orders that led to almost the entire room of guests being without masks during the later evening activities."

The letter also includes a confirmation of the violation, which is a first-time warning, that lays out a fine of up to $15,000 for each potential future violation.

Trump has consistently downplayed wearing masks over the course of the entire pandemic. Despite telling people to wear masks on occasion at official briefings, he also mocked others for wearing them, including President-elect Joe Biden. Many supporters have decried mandates and openly flouted rules, including maskless Trump supporters who stormed the Capitol last week.

ABC News' Will Gretsky contributed to this report.