On Friday, the Centers for Disease Control and Prevention released three studies that show that COVID-19 infections were more pervasive in areas that did not require masks in schools.

The studies provide further evidence that the CDC's recommendation that teachers, staff and students wear masks when in school significantly lessen the spread of COVID-19.

One of the studies, which was conducted in Arizona, showed that schools that did not require universal masking were 3.5 times more likely to have a COVID-19 outbreak than schools that did require masks.

A second study found that the case rates of COVID-19 among children were nearly half as low in counties that require masks in schools compared to counties that did not require masks in schools. In counties that required masks in schools, the pediatric case rate was 16.32 per 100,000, compared to 34.85 for counties that did not require masks in schools.

CDC

A third study concluded that 1,801 schools across the country have had to close at some point this school year due to COVID-19 outbreaks. The number of closures was highest in the South, where more governments have taken action to limit the use of masks in schools.

Still, the CDC said Friday that 96% of schools across the country have been able to remain open for in-person learning during the 2021-22 school year.

"These studies continue to demonstrate the importance and effectiveness of CDC's Guidance for COVID-19 Prevention in K-12 Schools to help districts ensure safer in-person learning and stop the spread of COVID-19," the agency said in a statement. "Promoting vaccination of eligible persons, mask wearing, and screening testing are all proven methods to continue to work towards the end of the COVID-19 pandemic."

WASHINGTON, D.C. — In a major shift, the Centers for Disease Control and Prevention (CDC) announced Thursday that it’s easing its indoor mask-wearing guidance for fully vaccinated people.

At a White House briefing, CDC Director Dr. Rochelle Walensky said people who are fully vaccinated against COVID-19 no longer need to wear face coverings indoors or outdoors, in most settings.

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

Locations, such as health care facilities, will continue to follow their specific infection control recommendations, according to Walensky.

“This past year has shown us that this virus can be unpredictable, so if things get worse, there’s always a chance that we may need to make changes to these recommendations,” she said. “But we know that the more people who are vaccinated, the less cases we will have and the less chances of a new spike or additional variants emerging.”

Walensky said if you develop coronavirus symptoms, you should put your mask back on and get tested right away.

As for unvaccinated people, Walensky said they remain at risk of falling ill with COVID-19 or spreading the virus to others.

“You should still mask and you should get vaccinated right away,” Walensky advised those who haven't been vaccinated.

Watch the briefing below:

Walensky clarified later on in Thursday's briefing that the agency still recommends that masks be worn while traveling, including planes, trains and buses. Masks should also still be worn in transportation hubs, like airports.

The FAA reinforced that statement, tweeting, "If you are fully vaccinated, you are still required to wear a mask while at the airport and on the plane."

When asked if Thursday's decision was made to incentivize Americans to get vaccinated, Walensky said the agency was simply following the science. She said that there is now ample real-world evidence that vaccines are reducing the spread of the virus between fully-vaccinated people.

Fauci added during the briefing that while the science now points to the fact that Americans no longer need to wear masks, there may be some who choose to continue to wear them. He said that there is "not at all" anything wrong with choosing still wear masks, and added that those people "shouldn't be criticized."

Later on Thursday, President Joe Biden delivered remarks about the CDC's updated mask guidelines, during which he called the new guidance "a great milestone."

"Just a few hours ago, the Center for Disease Control and Prevention, the CDC, announced that they are no longer recommending that fully vaccinated people need wear masks. This recommendation holds true whether you are inside or outside. I think it's a great milestone, a great day," he said.

The CDC last updated its guidance for vaccinated people on April 27. In that update, the CDC said that fully-vaccinated Americans could safely participate in outdoor activities without a mask, so long as those activities did not involve large crowds.