People over 75, front-line essential workers should get vaccine next, CDC panel says

The United States set a new record for hospitalizations on Monday, the COVID Tracking Project reported.

At least 110,549 Americans are currently hospitalized for COVID-19, according to the health data.

"AZ and NV have the highest hospitalizations per million people in the country. Current hospitalizations in AZ have surpassed the state's peak in the summer," the tracking project tweeted.

The seven-day averages for key health data points also reached new records Monday, the tracking project reported.

The seven-day average of newly recorded cases was 213,293, the seven-day average for newly reported hospitalizations was 107,856 and the seven-day average for newly recorded fatalities was 2,435, according to the health data.

Members of the National Guard will help distribute the COVID-19 vaccine in 26 U.S. states and territories, a National Guard official said during a press briefing Monday.

National Guard commanders from Ohio, West Virginia and Oklahoma detailed the limited role their members will play in their respective states.

It will work with state departments of health to break down the large 975-batch Pfizer packages into smaller packages as needed, and use rented vehicles and equipment to transfer packages from main hubs to satellite sites for further distribution.

ABC News' Matt Seyler contributed to this report

The number of confirmed deaths from COVID-19 in the United States surpassed 300,000 on Monday, according to real-time data from Johns Hopkins University.

The grim milestone comes after the U.S. logged 3,124 fatalities from the disease in a single day last week, the highest one-day COVID-19 death toll the country has reported since the pandemic began.

One of the biggest unanswered questions scientists have about the COVID-19 vaccine is how long virus protection will last after people get two doses.

While more research needs to be done before any official guidance is released, Dr. Peter Marks, director of the Center for Biologics Evaluation and Research at the U.S. Food and Drug Administration, said early vaccine trials may provide clues.

At the very least, a two-shot vaccination should offer at least several months of protection, Marks explained during an interview with the Journal of the American Medical Association on Monday.

"It's at least probably on the order of four to six months," Marks said. "The question is, will it reach out to a year? Hopefully, yes. But I think we’ll have those data in the not so different future."

ABC News' Anne Flaherty contributed to this report.