WASHINGTON - COVID-19 cases and hospitalizations have declined from recent surges across the United States, but health experts warn more contagious coronavirus strains may threaten to undo progress and lead to resurgence.

A total of 125,735 new COVID-19 cases were reported across the country on Monday, bringing the seven-day average daily increase of cases to about 144,000, according to data updated by the US Centers for Disease Control and Prevention (CDC) on Tuesday.

It was down about 42 percent from a peak of almost 250,000 new cases per day last month.

Hospitalizations nationwide have also dropped. There were 92,880 people hospitalized with COVID-19 across the United States as of Tuesday, according to The COVID Tracking Project.

"Compared to last week, the number of people currently hospitalized with COVID-19 is down by 10 percent or more in 38 states," said the tracking project.

The CDC recorded 1,876 new daily deaths nationwide on Monday. The seven-day average deaths declined more than 10 percent from last week in 25 states. Only nine states saw an increase of 10 percent or more in the same time frame, according to the tracking project.

As daily new deaths lag cases and hospitalizations by a few weeks, health experts expect that figure will start to fall in the near future as well.

Since Jan 1, more than 100,000 Americans have died from COVID-19 so far, according to Johns Hopkins University data.

In Los Angeles County, the most populous county in the United States, the COVID-19 death toll climbed above the 17,000-mark on Tuesday, though daily cases appeared to decrease.

Local public health officials warned that the pandemic could easily surge again if people grow complacent and stop adhering to health restrictions, particularly with the recent reopening of more businesses and Super Bowl scheduled for Sunday.

The Joe Biden administration announced Tuesday that it was moving to expand access to COVID-19 vaccines, freeing up more doses for states and beginning to distribute them to retail pharmacies next week.

As part of the US Federal Retail Pharmacy Program, chains CVS and Walgreens will begin administering vaccines starting next week. The White House listed 21 national pharmacy chains that will participate in the initial phase of the program.

The push came amid new urgency to speed vaccinations to prevent the spread of potentially more contagious coronavirus strains.

A total of 546 infection cases of coronavirus variants had been reported in at least 33 US states as of Tuesday, according to CDC data.

The vast majority of these cases, 541, were caused by the variant known as B.1.1.7, which was originally detected in Britain.

There were three cases of a new strain initially discovered in South Africa, called B.1.351, and two cases of the P.1 strain first discovered in Brazil.

Beginning Tuesday, Americans are required to wear face masks while traveling on domestic public transport as part of a national strategy to curb the spread of COVID-19.

The mask-wearing rule, which went into effect at 11:59 pm Monday (0459 GMT Tuesday), makes refusal to wear a mask a violation of federal law, enforced by the Transportation Security Administration and other federal, state and local authorities.