COVID-19 live updates: 7 states accounting for about half of new cases

These seven states have some of the lowest vaccination rates.

The United States is facing a COVID-19 surge this summer as the more contagious delta variant spreads.

More than 614,000 Americans have died from COVID-19 and over 4.2 million people have died worldwide, according to real-time data compiled by the Center for Systems Science and Engineering at Johns Hopkins University.

Just 58.3% of Americans ages 12 and up are fully vaccinated against COVID-19, according to data from the Centers for Disease Control and Prevention.

The CDC last week, citing new science on the transmissibility of the delta variant, changed its mask guidance to now recommend everyone in areas with substantial or high levels of transmission -- vaccinated or not -- wear a face covering in public, indoor settings.

The U.S. has seen 864,000 vaccinations in the last 24 hours, the highest daily number since July 3, White House coronavirus response coordinator Jeff Zients said Thursday.

Among those 864,000 vaccinations were 585,000 first shots -- the highest since July 1.

Zients said "Louisiana, Arkansas, Missouri, Alabama, Oklahoma and Mississippi are now vaccinating people at a pace not seen since April."

Tennessee has seen a 90% increase in first shots over the past two weeks and Georgia has recorded a 66% increase in first shots in the last two weeks.

However, seven states -- Florida, Texas, Missouri, Arkansas, Louisiana, Alabama and Mississippi – which have some of the lowest vaccination rates, "account for about half of new cases and hospitalizations in the past week, despite making up less than a quarter of the U.S. population," Zients said.

-ABC News’ Cheyenne Haslett

Yelp now has a feature that will allow businesses to list if they have vaccine requirements.

The feature was mentioned at the White House's COVID-19 briefing Thursday.

-ABC News’ Cheyenne Haslett

In Arkansas, one of the states hit hardest by the delta variant, Gov. Asa Hutchinson has reversed course, lifting a previously signed ban on mask mandates.

Hutchinson told "Good Morning America" Thursday that masks are not needed in schools if students are vaccinated but he's "particularly concerned" about kids under 12 who are too young to get the shot.

In those cases, he said, schools should have the option to enforce masks.

The governor added that he's pushing vaccine efforts with high school students and "making sure the faculty is vaccinated."

Moderna says its vaccine is 93% effective against symptomatic illness after six months (though this data collection ended before delta emerged in the U.S.).

Moderna said its booster candidates also demonstrate robust antibody responses to variants of concern, including delta.

Moderna President Dr. Stephen Hoge told "Good Morning America" Thursday that the Moderna vaccine offers protection from delta right after receiving it, but it's not known yet if that'll hold up through the winter. He called winter "the biggest test of that vaccine which is why we need to be vigilant and careful."

Hoge said he thinks booster shots will be needed and that the company is "preparing options," but he added that that'll be for public health officials, not the company, to decide.

He also noted that Moderna's goal is to be vaccinating kids under 12 by the end of the year. Moderna isn’t authorized for kids ages 12 to 17 yet, but Hoge hopes authorization could come “any day.”

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