Hall of Fame boxer Oscar De La Hoya said on social media Friday he is hospitalized with COVID-19.

Due to his illness, he won't be able to fight former UFC champion Vitor Belfort on Sept. 11 in Los Angeles, which would have been De La Hoya's first bout since 2008.

"Preparing for this comeback has been everything to me over the last months, and I want to thank everyone for their tremendous support," De La Hoya, 48, said in an Instagram post, noting that he is fully vaccinated. "I am currently in the hospital getting treatment and am confident I will be back in the ring before the year is up. God bless everyone and stay safe."

Florida Gov. Ron DeSantis filed an appeal against a court ruling invalidating his ban on student mask mandates Thursday evening.

The governor had banned school districts from implementing mask mandates without a parent opt-out.

The move unleashed a stay of proceedings that enables the state to continue punishing districts, at least until Wednesday, when a judge will decide whether to vacate the stay.

In the meantime, school board members across the state could continue to lose their salaries if their schools set mask mandates -- a punishment given to board members in two counties and threatened to those in eight others.

The appeal comes a week after Judge John C. Cooper found that a blanket ban on face masks in schools "does not meet constitutional muster.”

-ABC News' Will McDuffie

The country’s COVID death toll has risen to more than 643,000 and the number of cases stands at 39.5 million, according to data from Johns Hopkins University.

That means 1 out of 8 Americans has tested positive for COVID-19 and 1 out of 510 Americans has died of the virus.

Heading into Labor Day weekend health experts are urging the public, especially the unvaccinated, to act responsibly as the delta variant continues to fuel infections.

Holidays have proven to be a catalyst for virus spread in the U.S.

Last summer, shortly after Labor Day, the U.S. fell into its most significant viral surge of the pandemic.

Between the week following last Labor Day and Thanksgiving alone, the nation's daily case average surged by more than 400%.

-ABC News' Arielle Mitropoulos

Over "1.40M doses reported administered over yesterday's total, including 550K newly vaccinated and 96K additional doses," White House COVID-19 data director Cyrus Shahpar said Friday.

That's the highest dose total since July 1, he said.

So far over 175 million people, or 61.9% of the eligible population, are fully vaccinated.

Dr. Paul Offit, a member of the U.S. Food and Drug Administration's vaccine advisory committee, said a two-dose COVID-19 vaccine "appears to be enough" to curb infection, rather than adding a booster shot.

"You look at states in the United States that have high immunization rates with a two-dose vaccine, it appears the two doses appears to be enough to be able to control this infection," Offit, who is also the director of the Vaccine Education Center at Children's Hospital of Philadelphia, told ABC News on Thursday night. "I think the critical issue here is not going to be boosting the vaccinated. I think if we really want to get on top of this pandemic, it's going to be about vaccinating the unvaccinated."

The FDA's vaccine advisory committee is set to hold a key meeting on COVID-19 vaccine booster shots on Sept. 17, just three days before the Biden administration plans to begin offering the shots to Americans.

"If the companies or the FDA can make a case that there has been an erosion in protection against severe critical disease and that that erosion in protection against severe disease would be mediated or eliminated by a third dose, then we could move forward," Offit said. "But to date, we really need to see those data to be able to make that decision."