(CNN) — As the Biden administration works to speed up the country’s Covid-19 response, reopening schools has become one of the primary benchmarks of recovery. Across the country as vaccines are being administered to essential workers, often including teachers, calls for restarting in-person learning are growing more urgent.

Vaccine distribution, one of the key parts of getting schools to reopen safely, has been picking up recently, with the US averaging 1.3 million new shots per day last week, closing in on President Joe Biden’s aim of 1.5 million per day. Still, it’s early and a timeline for returning to in-person school remains a fierce topic of debate. While some states like Texas and Florida have ordered publicly-funded schools to be open, others like California and Illinois are locked in heated negotiations with teacher unions over the issue.

Republican lawmakers have renewed efforts to push schools to reopen. The House blocked immediate consideration last Tuesday of a Republican bill that would place new conditions on $54 billion in funds for K-12 schools passed by Congress in December, requiring schools to submit a plan to reopen in order to receive the majority of the money. Despite this setback, Republicans continue to call for schools to reopen.

“The evidence is clear: COVID-19 risk to kids in school is low,” Kentucky Rep. Andy Barr tweeted last week. “Meanwhile, the emotional cost to kids not having in-person learning is high.”

On the Senate floor, Minority Leader Mitch McConnell advocated for reopening schools, calling remote learning a “pale shadow of proper schooling,” and added that “all the science, all of it” points to being able to send kids back to school.

While the issue is complex and depends on the challenges different school districts face, studies — including ones from the Centers for Disease Control and Prevention — have shown that schools can safely reopen without creating outbreaks of the coronavirus if safety measures and precautions are followed. For some schools, like those in urban centers, ones held in older buildings and schools with large class sizes, the challenge of meeting those measures can be quite significant.

What the data shows

“There’s a lot of science suggesting that many schools can open up safely,” Harvard University epidemiology professor Marc Lipsitch said, before noting that some are in better position than others.

“Vaccines are an element of this,” Lipsitch added, though he was adamant that any vaccination plan to aid reopening schools should include not just teachers but other adults involved in the school’s ecosystem.

While discussing the rollout of Covid-19 vaccines and teachers being categorized as essential workers, CDC Director Rochelle Walensky said during a briefing last week that “there is increasing data to suggest that schools can safely reopen” and noted that “vaccination of teachers is not a prerequisite for safe reopening of schools.”

During a Friday press conference, Walensky said guidance for reopening schools would be issued this week. “Our goal is to get children back to school. School should be the last places closed and the first places open. Our goal is to make sure in getting children back to school that we do so both with the safety of the children and the safety of the teachers,” Walensky said.

Studies show encouraging data on schools reopening, with low rates of Covid-19 infections. In a study published January 26, several CDC researchers examined 17 schools in Wisconsin over the course of three months and found that the spread of the virus “among students and staff members was lower than in the county overall.” Several safety measures were instituted at the school, including mandatory mask-wearing, limiting group sizes of 11 to 20 students, and social distancing whenever possible.

According to the study, only 3.7% of the documented cases of coronavirus among staff and students “were linked to in-school transmission, and all seven were among children.”

One significant limitation of the study was that the schools observed were rural and the authors noted that physical distancing might be more challenging in urban and suburban schools.

This is not to say outbreaks at schools do not occur, but as an article published in JAMA last week noted, “there has been little evidence that schools have contributed meaningfully to increased community transmission.”

In order to prevent the transmission of Covid-19 in schools, the study recommended universal mask wearing, increased air ventilation in the schools, increased testing and “using hybrid attendance models when needed to limit the total number of contacts and prevent crowding.”

Reopening schools

Experts say there’s no perfect, cookie-cutter solution to safely reopen the 130,000 K-12 schools in the US. Safety measures depend on several factors including class sizes, as well as the average age of teachers and co-morbidities they may have and the age of the building and the ventilation of the school.

Mark Hernandez, who runs the Environmental Engineering Microbiology and Disinfection Lab at the University of Colorado and has worked with local schools to improve their ventilation systems, told CNN that “the design and operation of school HVAC systems have a significant influence” on students’ exposure to the virus throughout the school day. “But the reality is that many of our nation’s schools do not have HVAC systems operating up to modern performance standards,” added Hernandez.

Even if certain safety measures are followed, reopening schools is often not as simple as flipping a switch. In several states, for instance, local unions, school districts and governments are locked in substantial negotiations over restarting in-person learning.

During a press conference last Thursday, Lori Lightfoot, the Democratic mayor of Chicago, demanded the Chicago Teachers Union conclude negotiations and start in-person learning this week.

“Schools are safe,” Lightfoot said, noting the city’s $100 million investment to make Chicago schools safer from the virus included face coverings, ventilation and “other in-school safety measures.”

The Chicago Teachers Union, however, wanted certain conditions met before returning in-person, like allowing school staff to be vaccinated, increased testing and a lower Covid positivity rate in the city.

A tentative deal was struck Sunday for schools in Chicago to reopen in phases starting later this week. On Twitter, the Chicago Teachers Union stressed that no agreement has been finalized and that members were still reviewing the framework of the deal.

Cost of reopening

Becky Pringle, president of the National Education Association, told CNN that “public schools that especially serve our more marginalized students” don’t have the resources to implement the myriad of proposed safety measures.

“That’s why we need the federal government to step up and do it now so that we can get about the business of reopening our school safely,” Pringle said.

According to the American Federation of Teachers — a national union with 1.7 million members — facilitating a “safe and effective reopening” of public schools would require “at least $116.5 billion” in federal funding.

This figure includes safety measures like personal protective equipment as well as items like a 10 percent increase in “instructional staffing” and funds to provide students with a secure internet connection for students remote learning.

For his part, Biden is proposing $130 billion to help K-12 reopen as part of his $1.9 trillion stimulus package.

In December, the President set a goal for the majority of schools to reopen in his first 100 days in office. The goal was then paired down to include just Kindergarten through 8th grade.

It’s unclear how feasible Biden’s 100-day target is even as Democrats work to pass his stimulus plan through Congress.

If the government provides the necessary resources and funding, one expert said it would be tough but doable to make the changes needed to reopen safely. Hernandez, the University of Colorado engineering professor, said renovating ventilation systems in older schools across the nation in particular would be a challenge in that time frame.

“In our great country, could we get every school up to the most modern HVAC standards to significantly lower airborne exposure risks in the education environment? In 100 days? From an infrastructure perspective, that would be a tough one, but doable should our government and private sectors devote the resources and resolve to do so,” Hernandez told CNN.

The-CNN-Wire

™ & © 2021 Cable News Network, Inc., a WarnerMedia Company. All rights reserved.