Chicago Mayor Lori Lightfoot announced Monday afternoon that city workers will have to get their COVID-19 vaccines.

Lightfoot said that the city has been working with labor unions over the last several weeks to finalize plans.

"It's for the safety of all involved," she said.

Lightfoot did not immediately reveal a deadline or other details about her order.

All large gatherings in Honolulu will be suspended due to a dramatic uptick in cases, Mayor Rick Blangiardi announced Monday.

Health care workers are "pushed beyond their limits," the mayor said.

The ban begins Aug. 25 and will last for four weeks.

Five states have intensive care units over 90% full: Alabama (100%), Florida (92.82%), Georgia (92.95%), Mississippi (93.81%) and Texas (91.27%), according to federal data.

The South also leads the country with the highest case rates. Louisiana and Mississippi have the highest case rates, followed by Florida, Tennessee, Georgia, Arkansas and South Carolina, according to federal data.

More than 95.6% of counties are either reporting high (89.32%) or substantial (6.24%) community transmission, federal data shows. Just 4.41% of counties are reporting moderate or low transmission.

-ABC News' Arielle Mitropoulos

The Food and Drug Administration on Monday granted full approval of the Pfizer vaccine, becoming the first COVID-19 vaccine to transition from an emergency authorization status to full FDA approval.

The full approval indicates that Pfizer has shown enough effectiveness and safety data to meet the stringent Biologics License Application requirements, which includes at least six months of safety data from a majority of the volunteers in a large, final stage clinical trial.

Pfizer's full approval will pave the way for further vaccine mandates in both the public and private sector. Some businesses and state leaders have held off thus far, signaling they'd wait for full approval before imposing tighter requirements.

Federal, state and local health officials have also expressed optimism that full approval will help dissolve some of the lingering hesitancy around taking a shot that until now has been only authorized for emergency use.

Acting FDA Commissioner Janet Woodcock called Monday's announcement a "pivotal moment" made possible by a "rigorous and thorough review" done in record time.

"Working around the clock, FDA staff were able to complete the evaluation of this biologics license application in just over three months," she said. "This is an unprecedented timeline given the volume of review and the meticulous manner in which it was done, but we want to underscore that our efforts to move as quickly as possible have in no way sacrifice scientific standards for the integrity of our process."

President Joe Biden said Monday, "If you're one of the millions of Americans who've said that they will not get the shot until it has full and final approval of the FDA -- it has now happened.

-ABC News' Sasha Pezenik

A Tallahassee judge ruled Friday that Florida school boards can enact student mask mandates, going against Gov. Ron DeSantis, who in July issued an executive order that set off a public feud with school districts.

Judge John C. Cooper found that a blanket ban on face masks in schools "does not meet constitutional muster" and ordered the Florida Department of Education to stop enforcing a state rule that requires districts to allow parents to opt-out of mask mandates.

Cooper, over about two hours, picked apart the state's defense, saying the science presented during the weeklong trial did not support the state's argument against masking children.

Ten Florida school districts have adopted mask mandates for students this month. Two -- Broward and Alachua -- were sanctioned by the Florida commissioner of education, who said he would begin withholding the salaries of board members who voted to require masks.

DeSantis will "immediately appeal" the ruling, the governor's press secretary, Christina Pushaw, said in a statement. "This ruling was made with incoherent justifications, not based in science and facts," Pushaw said.

A spokesman for the Florida Department of Education said, "We are immensely disappointed that the ruling issued today by the Second Judicial Circuit discards the rule of law. This decision conflicts with basic and established rights of parents to make private health care and education decisions for children. ... We are committed to the fundamental rights of parents and will push forward on appeal to ensure that this foundation of democracy is upheld."

-ABC News' Will McDuffie