COVID cases in the U.S. have soared to record highs as the infectious Omicron variant continues to spread. Centers for Disease Control and Prevention (CDC) data showed the country had a seven-day moving average of just under 500,000 new cases on January 3.

The new seven-day moving average marks an approximately 230 percent rise over 14 days. In addition, the country hit over 1 million new daily cases on Monday, according to Johns Hopkins University.

It means the U.S. has far surpassed last winter's seven-day average peak of 250,000, which took place on January 11, 2021, CDC data shows. The number of current cases appears to still be rising.

On Tuesday President Joe Biden acknowledged in a White House press briefing that there was "concern and some considerable confusion" regarding the rising case numbers and said that the Omicron variant is "much different than anything we've seen before."

"We're seeing COVID-19 cases among vaccinated in workplaces across America, including here at the White House. But if you're vaccinated and boosted, you are highly protected," said Biden.

The president urged people to get vaccinated in order to curb the impact from rising case numbers, adding: "We have in hand all the vaccines we need to get every American fully vaccinated, including the booster shot."

It comes as 34.7 percent of the U.S. population have had a COVID booster vaccine as of January 4. In addition, the percentage of people over 18 who have had a booster is only slightly higher at 37.7 percent.

On Monday the Food and Drug Administration (FDA) announced that it had approved Pfizer booster doses for people aged between 12 and 15 as schools reopen after the holiday break.

The agency said it had reviewed real-world data from Israel, including safety data from over 6,300 people aged 12 to 15 who received a booster dose 5 months or more after their initial two doses.

"The data shows there are no new safety concerns following a booster in this population," the FDA said.

U.S. hospitalizations are also rising. CDC data shows that the seven-day average of new admissions of patients with COVID was at 14,776 between December 27, 2021, and January 2, 2022—not far off the January 2021 peak of more than 16,000.

On January 3 there were 1,559 new COVID deaths, bringing the seven-day moving average to 1,165. The seven-day moving average has remained at between 1,100 and 1,200 for much of December—lower than in October.

Meanwhile, thousands of schools across the country have delayed reopening this week or switched to remote learning.

In New Jersey, most urban school districts have implemented virtual classrooms as the new year begins, Reuters reports. Over the U.S. as a whole there were more than 3,500 K-12 public school closures going into the start of this week, according to school opening tracker Burbio.

COVID test site
People queue up outside a COVID testing site in New York on January 4, 2022. U.S. cases have risen sharply over the holiday break.Angela Weiss/AFP/Getty