The top US health agency has said it is lifting mask-wearing guidance for people who are fully vaccinated against Covid-19, a watershed moment that President Joe Biden called “a great day” in the long pandemic fight.

The announcement by the Centres for Disease Control and Prevention (CDC) marked an abrupt turnaround after more than a year of urging people to cover their faces to stem the spread.

“Anyone who is fully vaccinated can participate in indoor and outdoor activities, large or small, without wearing a mask or physical distancing,” CDC director Rochelle Walensky said during a briefing.

“If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic.”