• The CDC announced new public health recommendations on masks Thursday.
• There are a handful of instances where people will still need to wear masks even if they've had their final vaccine dose two or more weeks ago.
• Masks will still be required in health-care settings, at businesses that mandate them or on public transportation.

Fully vaccinated people no longer need to wear a face mask or stay 6 feet away from others in most settings, whether outdoors or indoors, the Centers for Disease Control and Prevention said in updated public health guidance released Thursday.

There are a handful of instances where people will still need to wear masks — in a health-care setting or at a business that requires them — even if they've had their final vaccine dose two or more weeks ago, CDC Director Dr. Rochelle Walensky told reporters at a press briefing. Fully vaccinated people will also still need to wear masks on airplanes, buses, trains and other public transportation, she said.

"Anyone who is fully vaccinated can participate in indoor and outdoor activities, large or small, without wearing a mask or physical distancing," Walensky said. "If you are fully vaccinated, you can start doing the things that you had stopped doing because of the pandemic. We have all longed for this moment, when we can get back to some sense of normalcy."

Walensky said unvaccinated people should still continue to wear masks, adding they remain at risk of mild or severe illness, death, and risk of spreading the disease to others. People with compromised immune systems should speak with their doctor before giving up their masks, she said.

She added there is always a chance the CDC could change its guidance again if the Covid pandemic worsens or additional variants emerge.

"This is an exciting and powerful moment, it could only happen because of the work of so many who made sure we have the rapid administration of three safe and effective vaccines," she said.

The announcement from the CDC comes just ahead of the Memorial Day and Fourth of July parade season. President Joe Biden has said he hopes to see enough Americans vaccinated by Independence Day to safely hold outdoor gatherings.

Last week, Biden announced his administration's latest goals in the fight against the coronavirus: getting 70% of U.S. adults to receive at least one dose of a Covid-19 vaccine and having 160 million adults fully vaccinated by July 4.

As of Wednesday, more than 151 million Americans age 18 and older, or 58.7% of the U.S. adult population, have received at least one dose of a Covid vaccine, according to data compiled by the CDC. Roughly 116 million American adults, or 45.1% of the U.S. adult population, are fully vaccinated, according to the agency.

To reach the president's goal, the administration is working to make getting a Covid vaccine shot as simple and convenient as possible.

Biden is directing thousands of local pharmacies to provide walk-in vaccinations to people without appointments, a senior administration official told reporters last week. The Federal Emergency Management Agency will also support pop-up and mobile clinics, which are aimed at individuals who may otherwise have trouble reaching vaccination sites.

On Tuesday, the White House announced a new partnership with Uber and Lyft that will offer free rides to vaccination sites until July 4.

The new CDC guidance Thursday marks a turning point in the pandemic and is likely to encourage more Americans, especially those still hesitant about receiving the shots, to get vaccinated, health experts say.

U.S. health officials stressed that the Covid vaccines are highly effective, pointing to several studies, including one out of Israel that found the Pfizer-BioNTech shot was 97% successful in preventing symptomatic infections in fully vaccinated people.

Dr. Paul Offit, director of the Vaccine Education Center at Children's Hospital of Philadelphia and a member of the FDA's advisory panel, called the new guidance an "important step forward."

"And yet another incentive to get vaccinated," he added.

The guidance is "pragmatic [and] aligns with science," said Dr. Isaac Bogoch, an infectious disease specialist at the University of Toronto. "It also demonstrates how mass vaccination can truly be a path toward normalcy and that the U.S. is far along on that path."

He added it will be "nearly impossible" to enforce with those who aren't vaccinated and said some businesses that lift restrictions may need to impose an honor system.

– CNBC's Rich Mendez contributed to this report.