By Paul LeBlanc, CNN

(CNN) -- President Joe Biden on Thursday touted new mask guidance from the US Centers for Disease Control and Prevention as "a great day for America" and an important milestone in the US coronavirus response.

Appearing maskless during remarks in the White House Rose Garden, Biden said, "You have 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 have gotten to this day."

His comments came hours after the CDC announced that people who are fully vaccinated against Covid-19 do not need to wear masks or practice social distancing indoors or outdoors, except under certain circumstances.

In a sign of the Biden administration's embrace of the guidance, the White House emailed staffers Thursday telling them they no longer have to wear a mask on the complex's grounds if they are vaccinated, an official told CNN.

"If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic," Dr. Rochelle Walensky said during a White House Covid-19 briefing. "We have all longed for this moment when we can get back to some sense of normalcy."

Calling it an "exciting and powerful moment," Walensky said the science supports the updated CDC guidance that "anyone who is fully vaccinated can participate in indoor and outdoor activities -- large or small -- without wearing a mask or physical distancing."

While Biden trumpeted that message, he stressed the need to continue vaccinating at an aggressive clip in order to drive transmission numbers lower.

About 45% of US adults are fully vaccinated against Covid-19, according to data published Wednesday by the CDC.

This is a breaking story and will be updated.

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