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

Japan has suspended the use of about 1.63 million doses of Moderna's COVID-19 vaccine due to reported contamination, as the country grapples with surging infections.

Japanese drugmaker Takeda Pharmaceutical Co., which is in charge of distributing the Moderna vaccine in Japan, said in a press release Thursday that it has received reports of foreign substances in some unused vials at multiple inoculation sites. Although some doses might have been administered, Takeda said there have been no reports of safety concerns tied to the affected vials so far.

After consulting with Japan's Ministry of Health, Labor and Wealth, Takeda said it decided as a safety precaution to stop using doses from three separate lots, manufactured in the same production line as the contaminated vials. The company said it has requested Moderna to conduct an emergency investigation into the issue.

For doses from non-suspended lots, Takeda urged people to check the vials for discolouration, foreign substances or other abnormalities before continuing to use. Meanwhile, the Japanese health ministry said it will work with Takeda to supply alternative doses in an effort to minimize the impact on the country's vaccination progress.

Moderna told ABC News that it has put the 1.63 million doses on hold in Japan after being notified that some of the vials may have been contaminated. One of the three lots received "several complaints of particulate matter" in its vials, the American drugmaker said, while the two other adjacent lots were put on hold out of "an abundance of caution" and for continued assurance of quality.

According to Moderna, the manufacturing issue may have come from one of the lines used at its contract manufacturing site in Spain. The Massachusetts-based company said it is looking into the contamination reports and "proactively communicating with Japan’s health authorities and its partners as the investigation proceeds." Moderna added that it remains "committed to working transparently and expeditiously" with its Japanese distribution partner and with regulators to address any potential concerns. No safety or efficacy concerns have been identified so far, the company said.

Moderna noted that the pause in Japan does not impact doses distributed in the United States, or put the American supply at risk in any way.