Updated

The White House says COVID-19 vaccinations are "picking back up" with more than 790,000 administered in 24 hours over the weekend, as the delta variant of the novel coronavirus becomes more prominent in the U.S. 

White House Chief of Staff Ron Klein touted vaccination data tracked by the Centers for Disease Control and Prevention. 

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"Vaccinations picking back up — about 790k in past 24 hours per @CDCgov report," Klein tweeted. "Might be the biggest 24-hour period since early July.  Thanks to everyone involved."

White House COVID data director Cyrus Shahpar also touted Sunday’s vaccinations, saying more than 489,000 Americans who revived a vaccine Sunday are "newly vaccinated." 

"Sunday in: +779K doses reported administered over yesterday’s total, including 489K newly vaccinated," he tweeted. "7-day average of newly vaccinated is up 28% over week prior! 69% of adults with at least one dose."

Shahpar was referring to the increase in newly vaccinated Americans amid vaccine hesitancy and concerns about the delta variant strain of the virus. 

According to the CDC, more than 163 million Americans have been fully vaccinated, while more than 188 million Americans have received at least one dose of a COVID vaccine. 

The delta variant has ripped through the unvaccinated population in America, with CDC Director Dr. Rochelle Walensky saying the variant is "spreading with incredible efficiency and now represents more than 83% of the virus circulating the United States."  

But even as the CDC and the Biden administration warn about the severity of the delta variant for those who are unvaccinated, some Americans remain hesitant to receive a vaccine. 

The persistence of hesitancy has "frustrated" Dr. Anthony Fauci, who thought the rise of the delta variant would push more people to get the shots. Instead, leaders are "practically pleading" with unvaccinated individuals. 

"What I would really like to see is more and more of the leaders in those areas that are not vaccinating to get out and speak out and encourage people to get vaccinated," said Fauci, the head of the National Institute of Allergy and Infectious Diseases.

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And last week, the White House said unvaccinated individuals "should be more fearful" amid the threat of the delta variant of COVID-19.

In this July 22, 2021 file photo, Soile Reyes, 12, of Brooklyn, receives the first dose of the Pfizer COVID-19 vaccine as her mother, Evelyn Pereira, looks on at the American Museum of Natural History in New York.  (AP Photo/Mary Altaffer) (AP Photo/Mary Altaffer)

White House press secretary Jen Psaki cited a CBS News poll that showed that vaccinated Americans are more fearful about the delta variant than unvaccinated people. 

"That’s clearly concerning to us because unvaccinated people should be more fearful," Psaki said.

Meanwhile, Walensky, during the COVID briefing on last week, maintained that unvaccinated individuals "need to be wearing a mask to protect yourself and others around you." 

"We need more people to get vaccinated to stop this pandemic," she said, adding that the CDC recommendations "haven’t changed," but warned that if individuals are in an area that has a high case rate and low rate of vaccination, "you should certainly be wearing a mask." 

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"If you are unvaccinated, if you are vaccinated, you get exceptional protection from the vaccines, but you have the opportunity to make the personal choice to add extra layers of protection if you so choose," Walenksy said. 

Walensky also urged Americans who are hesitant to get vaccinated to speak with their health care providers and friends and family to ask questions before making the "critical decision." Walensky also urged the unvaccinated to "continue to do the things that we know worked to protect you and your family until you are fully vaccinated." 

Walensky added that unvaccinated individuals should take the delta variant "very seriously." 

"If you are not vaccinated, please take the delta very seriously. This virus has no incentive to let up and it remains in search of the next vulnerable person to infect," Walensky said. "Please consider getting vaccinated and take precautions until you do." 

As for masks, the White House says there has been no change in its guidance — vaccinated individuals do not need to wear face coverings, and unvaccinated individuals should continue to wear masks.