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President Biden on Tuesday maintained that COVID-19 is an illness of those who refuse the vaccine, stating that people who have not gotten shots should be "alarmed" by the highly-transmissible Omicron variant even as it rampages through the vaccinated population.

"There is no excuse — no excuse for anyone being unvaccinated," Biden said during remarks from the White House following a briefing from his COVID-19 response team. "This continues to be a pandemic of the unvaccinated. So we got to make more progress."

But those who have been vaccinated are still getting sick.

The U.S. recorded its record number of COVID-19 cases for a single day on Monday, almost doubling the previous record of about 590,000 set just four days earlier. This, despite 73% of the U.S. population being at least partially vaccinated and 62% fully vaccinated, according to the Centers for Disease Control.

Biden suggested that vaccinations would "protect" people from getting the illness.

"Omicron is a very transmissible, transmissible variant, but much different than anything we've seen before," Biden said. "You can protect yourself, and you should protect yourself, quite frankly. Get vaccinated, get boosted. There are plenty of booster shots. Wear a mask while you're in public." 

U.S. President Joe Biden speaks while joining the White House Covid-19 Response Team's call with the National Governors Association discussing the Omicron variant in the Eisenhower Executive Office Building in Washington, D.C., U.S., on Monday, Dec. 27, 2021. Biden's medical adviser said a domestic travel vaccination rule should be considered as the omicron variant fuels record Covid-19 case loads in some states and holiday travel continues to be disrupted around the U.S. Photographer: Ken Cedeno/UPI/Bloomberg via Getty Images

U.S. President Joe Biden speaks while joining the White House Covid-19 Response Team's call with the National Governors Association discussing the Omicron variant in the Eisenhower Executive Office Building in Washington, D.C., U.S., on Monday, Dec. 27, 2021. Photographer: Ken Cedeno/UPI/Bloomberg via Getty Images (Ken Cedeno/UPI/Bloomberg via Getty Images)

But the CDC noted on Dec. 20 that it "expects that anyone with Omicron infection can spread the virus to others, even if they are vaccinated or don’t have symptoms." 

BIDEN'S 'PANDEMIC OF THE UNVACCINATED' NARRATIVE FALLS APART AS OMICRON CASES SKYROCKET

Biden admitted that those who are fully vaccinated and boosted "can still get COVID-19," but said it is "highly unlikely" that those individuals become "seriously ill." 

According to Johns Hopkins Medicine, "The symptoms of breakthrough COVID-19 are similar to COVID-19 symptoms in unvaccinated people, but are generally milder," though the vaccines "are very effective" at preventing hospitalization and death.

Biden warned that those who are unvaccinated "have some reason to be alarmed." 

"Many of you will, you know, you'll experience severe illness in many cases if you get COVID-19 if you are not vaccinated," Biden said. "Some will die, needlessly die. Unvaccinated are taking up hospital beds and crowding emergency rooms and intensive care units." 

The president said there is "concern and some considerable confusion" about the rising cases of COVID-19 across the nation. 

Biden said the COVID-19 testing situation in the United States is "frustrating" but maintained that his administration is "making improvements" by creating federal testing sites and making more at-home rapid tests available to the public. 

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As for testing, the president said the system "remains frustrating." 

"Believe me, it's frustrating to me," Biden said. "But we're making improvements." 

The president said that in the last two weeks, his administration has set up federal testing sites across the country, and is adding more "each and every day." Biden encouraged individuals to "Google 'COVID test near me' to find the nearest site where you can get a test most often and free." 

Biden also said that the increased capacity for in-person testing will reduce lines and make more appointments available. 

As for those looking to test at home, Biden said drug stores and online websites "are re-stocking," saying more at-home tests will "continue to become available." 

The president also announced that next week, insurance companies will begin reimbursing individuals for at-home rapid tests. 

"If you're insured, you can buy the test and get paid for it," Biden said, adding that many states and local governments are "passing out free at-home tests that you can pick up." 

"Just find out where they are," Biden said. 

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The president also added that the federal government is launching a website in January where individuals can go and request tests to be shipped to their homes for free.

During his remarks, Biden also announced that he had directed health officials to double the U.S. government's purchase of Pfizer's antiviral COVID-19 pill from 10 million to 20 million treatment courses and planned to accelerate the delivery of those treatments. 

The Food and Drug Administration granted emergency use authorization for Pfizer's Paxlovid-nirmatrelvir tablets and ritonavir tablets last month – the first oral antiviral treatments for COVID-19.

The Biden administration in November had announced a commitment to securing 10 million treatment courses of Pfizer's Paxlovid oral antiviral drug, contingent on the FDA's emergency use authorization. The administration paid $5.295 billion for the first 10 million courses. 

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The drug has been developed to treat non-hospitalized, symptomatic adults diagnosed with COVID-19 who are at increased risk of progressing to severe illness that could lead to hospitalization or death.

The president again urged individuals to wear masks in public.

Fox News' Jessica Chasmar contributed to this article.