The guidance does not specifically mention schools, so it remains unclear what it means for students in the Philadelphia area.
The Philadelphia Federation of Teachers union released a statement in response to the CDC's announcement, saying, "We will evaluate the guidance for how it will apply to school settings, and how it might apply especially in younger grades where students are not yet eligible for vaccination."
In Montgomery County, Springfield Township School District officials say they are also reviewing the new guidance.
"What we do know is the number one goal for us is for families to be confident to have their children in school, so that will be a major factor in any decision," said Dr. MaryJo Yannacone, the superintendent with the school district.
SEE ALSO: Pennsylvania will follow CDC's mask guidance for fully vaccinated residents
The CDC says state, local and business rules must be observed.
And the new guidance still calls for wearing masks in crowded indoor settings like buses, planes, hospitals, prisons and homeless shelters.
Pennsylvania has said it will follow the CDC's recommendation.
The Philadelphia Department of Public Health has not made a decision at this time.
Health officials in New Jersey and Delaware say the CDC's new mask guidance is under review.
Teachers union president is 'all in' on full fall reopening
The president of the American Federation of Teachers said Thursday there should be a full return to in-person learning in the fall and her union is "all in" on bringing students back to the classroom.
In an address on social media, Randi Weingarten said the wide availability of vaccines and a new infusion of federal education money have removed many obstacles that prevented schools from opening.
"Conditions have changed," Weingarten said. "We can and we must reopen schools in the fall for in-person teaching, learning and support. And keep them open. Fully and safely, five days a week."
If local unions heed her call, it would be seen as a major stride in the effort to reopen schools. Teachers unions have been blamed for slowing the process with demands for a variety of safety measures. Teachers in some districts have refused to return until ventilations systems are updated, virus tests are given and all teachers are vaccinated.
Weingarten said vaccines have been the decisive factor in her vision for a fall reopening. President Joe Biden in March ordered states to prioritize teachers in vaccination rollouts, and by the end of that month, federal health officials said 80% of school workers had been given their first shot.
"I hear it in educators' voices and see it in our polling results," the union chief said. "The fear that they will bring the virus home decreases the moment educators get the shots."
Surveys by the union find that 89% of its 1.7 million members have been fully vaccinated or want to be, she said.
Still, Weingarten isn't suggesting a quick return to the type of schooling students knew before the pandemic. She said schools should continue with mask requirements, social distancing, contact tracing and other measures recommended by the Centers for Disease Control and Prevention.
"It's not risk free," Weingarten said. "But we can manage the threat by encouraging people to get vaccines and following guidance from the CDC."
The union will continue to push for 3 feet of space between students in classrooms, which the CDC recommended in March after reducing it from 6 feet. Weingarten said schools should work over the summer to "find adequate space" to maintain smaller classes throughout the school year.
Her address came after a unanimous vote from the union's executive council approving her message for the fall.
A $1.9 trillion aid package that Biden signed in March included $123 billion to help schools reopen and recover from the pandemic. Weingarten, who endorsed Biden, wrote that his administration has been "fighting the pandemic with science, truth, transparency and, yes, money."
"The United States will not be fully back until we are fully back in school. And my union is all in," she said.
The CDC has been saying since February that schools can safely reopen with certain safety measures, but many of the nation's largest districts have remained mostly or entirely online. The latest federal data found that, in March, 54% of public elementary and middle schools were offering five days a week of in-person instruction to all students.
Even in districts that have reopened, many students have opted to stay at home, including a disproportionate share of nonwhite students. Weingarten is suggesting that schools create committees of parents and teachers to tackle safety issues. That, along with continued safety measures, would help rebuild trust with families, she said.
The union is also coming out with a $5 million campaign to push for a fall reopening. The group said it will reach out to teachers, families and communities to highlight the value of getting all students back in the classroom. A local union in Pittsburgh plans to go door to door talking about safety measures in place in schools. Other local groups are helping operate vaccination clinics for students and families.
"When I tell you we're all in," Weingarten says, "we're all in."
The Associated Press contributed to this report.