The shift reflects the spread of the omicron variant.
As the COVID-19 pandemic has swept the globe, more than 5.3 million people have died from the disease worldwide, including over 816,000 Americans, according to real-time data compiled by Johns Hopkins University's Center for Systems Science and Engineering.
About 61.7% of the population in the United States is fully vaccinated against COVID-19, according to data from the Centers for Disease Control and Prevention.
Pfizer's at-home pill treatment for COVID-19 was authorized by the FDA on Wednesday.
When taken early, Pfizer's pill was 89% effective at reducing the risk of severe illness and death from COVID-19, according to the company.
It's also effective against omicron, Pfizer said.
-ABC News' Cheyenne Haslett
President Joe Biden received another PCR test Wednesday and again tested negative following exposure to a staff member who recently tested positive for COVID-19, the White House said.
Biden was near the staff member for about 30 minutes on Air Force One on Friday, during a trip to Philadelphia from South Carolina, according to White House press secretary Jen Psaki.
The staff member, who is fully vaccinated and boosted, tested negative Friday morning but tested positive Monday, according to the White House.
The president first received an antigen test Sunday and a PCR test Monday and both came back negative, Psaki said.
-ABC News' Sarah Kolinovsky
Delta Air Lines said the omicron surge "may exacerbate shortages and create significant disruptions."
Delta is urging the CDC to shorten the time fully vaccinated people must isolate following breakthrough infections, saying the current 10-day period "may significantly impact [its] workforce and operations."
Delta proposed a five-day isolation from symptom onset for those who experience a breakthrough infection.
"Our employees represent an essential workforce to enable Americans who need to travel domestically and internationally," Delta said in a letter.
Ninety percent of Delta's workforce is fully vaccinated.
-ABC News' Amanda Maile
The United Kingdom recorded 106,122 new cases in the last 24 hours, surpassing 100,000 daily cases for the first time, according to government data.
That brings the total of cases over the past seven days to 643,219 -- a 58.9% jump from the previous week.
Deaths, however, are not rising. This week's death toll is down 2.7% from the week before.
-ABC News' Guy Davies
