That's according to data from event information website Burbio, which has been tracking K-12 U.S. school reopenings, given to Fox News.
The CDC advises that schools in the red zone meet stricter reopening standards, including a hybrid model of in-person and virtual learning, or reduced attendance for elementary school students.
The CDC's mitigation strategy as part of its new school reopening guidance released last week includes color-coded community zones; the blue zone represents zero to nine new cases per 100,000 people, the yellow zone represents 10-49 new cases per 100,000, the orange zone represents 50-99 cases per 100,000 and the red zone represents more than 100 new cases per 100,000 – or at least 0.1%.
Schools in all tiers are expected to implement mandated mask-wearing, 6-foot social distancing measures, regular facility cleanings and contact tracing and diagnostic testing.
Red-zone schools must go beyond that by offering hybrid learning for elementary students, require online learning for middle and high school students unless schools are already opened – in which case they would have to implement all mitigation strategies – and offer only virtual sports and extracurricular activities.
"We calculate that 93% of the students currently attending 'traditional' schools live in the red tier," a Burbio spokesperson told Fox News.
The spokesperson noted that the CDC's guidelines "don't call for the closing of schools currently educating students in-person, but by following the CDC guidelines, districts in 'Always Virtual' areas will need to meet higher standards to introduce in-person learning than districts that have opened earlier this academic year."
The CDC is not requiring teachers to be vaccinated before schools reopen as part of its new guidance despite pleas from teachers unions, but teachers are next in line to get the vaccine, along with other front-line essential workers and people over 65 years old, in line with CDC recommendations.
Biden and national teachers unions applauded the CDC's reopening guidance as a productive next step to reopening schools, which the president said he aims to achieve by his 100th day in office.
"These scientific guidelines tell us that our schools are safer when we have appropriate distancing in classrooms and on school buses, when masks are worn consistently and properly, when handwashing occurs regularly, and when we are able to effectively respond to cases through testing and contact tracing, and when we follow other recommended steps," Biden said in a Feb. 12 statement in response to the news.
He continued: "To meet these guidelines, some schools will need more teachers and support staff to ensure smaller class sizes, more buses and bus drivers to transport our kids safely, more spaces to conduct in-person instruction, and more protective equipment, school cleaning services, and physical alterations to reduce the risk of spread of the virus."