"We remain concerned about the continued rise in cases, driven by the Delta variant," said White House COVID-19 response coordinator Jeff Zients, noting the cases were concentrated in communities with low vaccination rates against the coronavirus.
One in three cases nationwide occurred in Florida and Texas in the past week, he told reporters on a conference call.
Meanwhile, more people have been vaccinated as concern about the variant spreads.
Zients said over the past few weeks there had been a nearly 70 percent increase in the average number of new people being vaccinated every day. Three million Americans had received their first shot in the last seven days, and the country reached a milestone on Monday of 70 percent of adults having at least one vaccine shot.
"There are still about 90 million eligible Americans who are unvaccinated, and we need them to do their part," he said.
U.S. Centers for Disease Control and Prevention Director Dr. Rochelle Walensky said that as of Saturday there were about 72,000 new cases per day of COVID-19 in the United States, a 44 percent increase over the previous week and higher than the peak set in the summer of 2020.
Hospital admissions had increased 41 percent and deaths had increased to 300 per day, a 25 percent jump, she said.
"While we desperately want to be done with this pandemic, COVID-19 is clearly not done with us. And so our battle must last a little longer," Walensky said.
The White House is working with states to encourage vaccinations using incentives, following President Joe Biden's call last week for states to use federal funds to pay $100 to anyone who gets inoculated, Zients said.
He said the White House's policy of urging all federal employees to get vaccinated or face weekly COVID-19 tests was helping spur more workplaces to implement similar policies for their employees, adding that vaccination requirements to return to work or school were a growing trend.
Walensky said the CDC is encouraging people who have decided to get a third booster shot to report data to government scientists.
"If people have taken the initiative to get their third shot - again, not yet recommended - but we have the capacity and are looking at those data right now," Walensky said. Reporting by Jeff Mason and Carl O'Donnell; Editing by Chris Reese and Dan Grebler