President Joe Biden told Americans on Thursday that the lifting of the rule on indoor mask-wearing was "a great day" in the fight against Covid-19 and that they could now "smile again."

"I think it's a great milestone, a great day," he said in a nationally televised address at the White House.

In often emotional remarks, Biden declared a major victory in the more than year-long battle which has seen more than half a million Americans die.

However he noted that the Centers for Disease Control (CDC) decision to stop recommending masks for all indoor activities applied only to people who have received both shots of vaccines.

Biden implored those yet to be completely vaccinated to keep wearing masks for now.

"Please protect yourself until we get to the finish line. Because as great as this announcement is, we don't want to let up. We all know how tough this virus us. The safest thing for the country, is for everyone to get vaccinated," he said.

Biden spoke about the hundreds of thousands of deaths and the lives upended for millions more as they missed family gatherings and important rituals.

The Democrat then heaped praise on ordinary Americans who, he said, had met the challenge head on -- and better than in some other countries.

"You've endured all this. When your country asked you to get vaccinated, you did. The American people stepped up. You did what I consider to be your patriotic duty. That's how we got to this day. As president, I can say I'm pleased... but not surprised," he said.

"As the virus tragically rages in other countries, as other nations, even wealthy nations, are mired in the challenges of slow vaccine rollout and poor economic conditions, things are very different here."

Biden noted that coronavirus cases are down in 49 of 50 states, saying deaths were down 80 percent to their lowest level since April 2020, when the disease was just taking a grip.

However, "it's going to take a little more time," he said. "Most people under the age of 65 aren't vaccinated yet."

Although pleading for patience, he invited those vaccinated to once again experience the pleasure of smiling.

"Take your mask off. You've earned the right to do something that Americans are known for all around the world: greeting others with a smile," he said.

"As tough as this pandemic's been, we will get through it. We will rebuild our economy, reclaim our lives and get back to normal," he said.

"Laugh again, we'll know joy again and we'll smile again. Now, we'll see one another smile, look at the smiles on other people's faces."