Christie reveals he spent 7 days in ICU and admits he was 'wrong' to not wear a mask

I hope that my experience shows my fellow citizens that you should follow CDC guidelines in public no matter where you are and wear a mask to protect yourself and others."

On "Good Morning America" Friday, Christie said he made "a big mistake" by letting his guard down on the White House grounds, "and it cost me in a significant way."

"I was led to believe that all the people I was interacting with had been tested and it gave you a false sense of security," he said.

Asked if the White House has learned the same lessons, Christie said, "I think we should be even more affirmative" with telling others to wear masks.

"Leaders, all across the politics, sports, the media, should be saying to people, put your masks on and be safe until we get a vaccine that could help to protect us," he said.

The warning from Christie stands in stark contrast to Trump's message since testing positive himself.

After departing from Walter Reed National Military Medical Center earlier this month, the President told his followers the virus that had hospitalized him for 72 hours was nothing to fear before posing for a mask-less photo op on the White House balcony.

"Don't be afraid of Covid.

Don't let it dominate your life," Trump had written several hours before walking carefully out the hospital's front doors, even as his doctors warned that he wasn't yet "out of the woods."

Noting that the US "may seem very divided today," Christie ended his statement Thursday with a call to action -- urging people to follow best public health practices while reopening as many businesses as possible.

"It is never too late to start.