White House coronavirus task force member Adm. Brett Giroir said the U.S. is facing "the worst rate of rise in cases that we've seen."

"This is not crying wolf," he stressed in an interview on MSNBC.

Though "vaccines are around the corner," Giroir said, state and local officials must be "very rigorous" about limiting certain businesses, limiting crowds in indoor spaces and enforcing mask use.

"If we do not do that, we will lose tens of thousands of Americans by the time the vaccine is out and widely distributed," he said.

Giroir also urged Americans to remember that a negative test is not a "free pass" to forgo masks and social distancing over the holidays.

"That negative test today does not mean you're going to be negative tomorrow or the next day, and certainly not by Thanksgiving. And it is not a free pass to go without all the important measures that we want, particularly mask wearing, physical distancing and following all the recommendations that the CDC has for the holidays," Giroir said.

ABC News' Brian Hartman contributed to this report.

South Korea is on edge after a surge in new COVID-19 cases this week.

Since the outbreak in late February, South Korea has mostly maintained low COVID-19 number.

But this week this country is seeing a steady increase and hit the highest in 81 days at 313 newly confirmed cases.

South Korea now has 29,311 cases and 496 deaths.

ABC News' Joohee Cho Christine Theodorou contributed to this report.

Delta Air Lines will continue to block middle seats through March 2021 "because customers tell us that adds confidence to their travel experience," CEO Ed Bastian told "GMA 3: What You Need to Know."

Bastian stressed that Delta hasn't "pulled back at all with our safety and cleaning protocols."

"Every airplane gets sanitized with electric spray fogging before we take off. We continue to focus on the filtration systems ,and they're state-of-the-art, and customers are required to wear masks," he said. "We don't have a single documented transmission of COVID aboard any of our planes."

"While travel is slow, it's steadily improving," Bastian said. "We're expecting over the Thanksgiving holiday period, starting on Friday for the next 10 days, about 2 million customers."

ABC News' Andrea Amiel and Lataya Rothmiller contributed to this report.

Jim Gentile is one of hundreds of registered nurses who have gone on strike at St. Mary Medical Center in Langhorne, Pennsylvania, some 25 miles northeast of Philadelphia. The nurses and their union say the main issue is inadequate staffing due to low wages, which they fear will only worsen as COVID-19 hospitalizations increase over the winter months.

"We're putting our foot down now because we know it's going to get twice as bad," Gentile told "Start Here," ABC News' daily news podcast.

Gentile, who works in the surgical services unit, said the hospital suspended all elective and non-emergency surgeries when the first wave of the coronavirus pandemic hit earlier this year. He and his coworkers were then sent to other floors to take care of COVID-19 patients.

"I did postmortem care on more bodies in two months than I have in 42 years of nursing. That's how bad it was," he said. "That's not my job. Usually, we wake people up from surgery and everybody's happy and we send them home. So this was really quite a shift."

The hospital resumed all surgeries over the summer and Gentile was able to return to his unit. But as COVID-19 hospitalizations tick back up, Gentile worries he and his coworkers will again be taken out of their area of expertise and sent to the coronavirus wards.

"In two weeks, we've doubled the number of COVID patients in our hospital," he said. "There are not enough nurses to take care of the patients."

The nurses on the picket line are fighting for a fair contract and better wages.

Gentile said the hospital desperately needs to hire more nurses to help care for the influx of COVID-19 patients, but the wages are too low and can't compete with other area hospitals. In the last two years, 243 nurses have left St. Mary's Medical Center, according to Gentile.

"When they showed us the wages, we realized no nurses are going to come to our institution with wages this low," he said. "We're not going to be able to recruit, we're not going to be able to retain."

Gentile, who has watched coworkers and friends die from COVID-19, said it's a matter of life and death.

"They don't understand the PTSD that nurses are going through and all they care about is keeping, you know, the budget, the bottom line, the margin," he said. "It doesn't matter how much money you've lost. We've lost family, we've lost friends. We put our lives at stake."

When asked for comment, a St. Mary Medical Center spokesperson told ABC News the hospital has offered a wage increase, which the nurses rejected, and that outside nurses have been hired to fill in during the strike.

"We respect the union members’ right to strike, and we remain committed to negotiating in good faith to reach agreement on a fair, consistent and sustainable initial contract for St. Mary nurses," the spokesperson said in a statement. "We look forward to the day productive negotiations can resume."

This report was featured in the Wednesday, Nov. 18, 2020, episode of “Start Here,” ABC News’ daily news podcast.

"Start Here" offers a straightforward look at the day's top stories in 20 minutes. Listen for free every weekday on Apple Podcasts, Google Podcasts, Spotify, the ABC News app or wherever you get your podcasts.

Pfizer said it's completed its submission to the Food and Drug Administration in which the company requests emergency use authorization for its vaccine.

The FDA is expected to start digging into the efficacy and safety data immediately, and it could make a decision as early as mid-December.

ABC News' Sony Salzman contributed to this report.