By Asaf Bitton, MD, MPH; Evan Benjamin, MD, MS, FACP; Margaret Ben-Or, MPH

Many K–12 schools in the United States are closing in on the end of their first term of the 2020–2021 school year, a year unlike anything we have experienced in recent history due to the COVID-19 pandemic. Some schools have opened their doors to full in-person instruction, others have adopted a hybrid model of remote and in-person learning, and still others have remained fully virtual. Planning for any of these models has been difficult and complex for school administrators, educators and staff, families, and students.

The planning discussions have rightfully centered the health and wellbeing of students and staff given the local context of the school community. The physical health and safety precautions have solidified around universal mask wearing, appropriate physical distancing, adequate ventilation, and hygiene considerations for both hands and surfaces. At the Parabola Project, a collaboration between Ariadne Labs and The Learning Accelerator, we have outlined nine public health principles for school reopening, which include those listed above, and others like leadership, symptom checking, and cohorting.

Some of these considerations begin to dig into complicated nuances — how far apart is far enough apart? If masks are on, can kids get closer to each other? — questions that researchers are still investigating. But the good news is that with the studies and evidence collected over the recent months, there is an emerging list of things we know that schools DO NOT need to do to stay safe. By busting a few of these “mythical” practices, school leaders can focus on allocating scarce resources elsewhere in order to implement the core public health playbook for COVID-19.

The myth of “deep cleaning”

In the early days of the pandemic, there were a lot of questions about SARS-CoV-2, the novel coronavirus that causes COVID-19. It was unclear, for example, how long the virus could survive on a surface, like door handles or cardboard boxes, and to what degree contaminated surfaces played in the transmission of the virus. Given this, many schools developed plans focusing on the need to frequently disinfect surfaces throughout the day and also to invest a significant portion of time weekly to “deep cleaning,” a nebulously defined idea for advanced sanitation. This specifically became a cornerstone of the cohort model of hybrid learning, in which cohorts of students alternate coming to school for in-person instruction. Many cohort models have cohort A in school Monday and Tuesday, cohort B coming to school Thursday Friday, with Wednesday reserved for virtual learning across cohorts to allow for “deep cleaning” of the school building.

Fortunately we have enough evidence to know that “deep cleaning” on Wednesdays — or any full day cleaning — is almost certainly unnecessary. While the virus can live for 24 to 72 hours depending on the surface, frequent disinfection with the appropriate products of high-touch surfaces like doorknobs and handrails and after each use of any shared items, with appropriate hand hygiene, is sufficient to lower the risk of infection. We also know now that while it is still important to disinfect surfaces, there is convincing evidence that transmission is largely driven by close proximity to someone who is infected — whether asymptomatic or symptomatic — through the respiratory droplets produced when that person coughs, sneezes, sings, talks, or breathes. The combination of frequent disinfection of high-contact surfaces, mask-wearing, frequent hand-washing, and proper ventilation eliminates the need for an entire day devoted to “deep cleaning.” As long as schools are able to commit to these practices, there is no need for staff to spend a full day cleaning before bringing a new cohort into the building.

The myth of plexiglass

The need to physically distance continues to present a challenge for schools. First, it limits the number of students who can fit in a classroom. Second, it presents the added complexity of how to allow kids to collaborate in small-group work, an important aspect of learning. Many schools have sought to solve the physical distancing challenge by investing sometimes exorbitant amounts of money to construct transparent, physical barriers using plexiglass or similar materials around students’ desks, thinking this will allow kids to move closer together. The problem is that, at best, these are an ineffective use of funds that could be allocated to more impactful practices, and at worst, the barriers create a new surface for potential contamination.

Unless a barrier expands from floor to ceiling, it does not provide protection from aerosols generated by infectious individuals with SARS-CoV-2 since we know the virus can stay suspended in the air for several hours. Put bluntly, a partial plexiglass sheet won’t do much to prevent aerosols from moving around a room. When used as a replacement for physical distancing or masks, it can create a false sense of security and protection. There are, of course, some notable exceptions to this rule. Barriers may offer modest additional protection to staff who interact with many people in a fixed location, sometimes with the inability to maintain six feet of distance, like front desk clerks and school nurses who may deal with hundreds of student interactions and for whom another barrier to droplets may be advisable.

However, using barriers creates an additional surface that may become contaminated — whether if touched by a person who hasn’t cleaned their hands or from an unmasked person talking — which means it is another surface that needs to be disinfected. This creates an additional burden for teachers or custodial staff tasked with frequent surface cleaning throughout the day, without a reciprocal benefit.

Where we should focus our efforts

Knowing that the above efforts are less effective, we can free up energy for public health practices we know are truly effective at stopping the spread of COVID-19:

Masks for everyone all the time in the school environment, even our youngest learners.

The evidence is clear — masks work to prevent the spread of COVID-19. Some parents have expressed concern that their kids, especially young children, will take off their masks and even swap them with their friends. In reality, what we’ve heard over and over again from educators is that students from kindergarten all the way up to high school seniors have no problem wearing their masks in school, especially if it allows them to be with their friends and teachers in the building. Those students who need a break can easily and safely do so in a designated area. Students understand the importance of mask-wearing to protect themselves and their friends, teachers, and families, especially when that message is supported at home and at school.

Maintaining six feet distance.

Distance and risk are related — the greater the distance between two individuals, the less risk of transmission. Some educators and parents have asked whether students can be closer together if both are wearing masks. There is no definitive evidence yet to confirm the risk of transmission in this scenario, though there are studies currently underway. Until those studies are complete, it is best to both mask up and keep adequate distance as much as possible. There are strategies for students to still work collaboratively in small groups while maintaining physical distance.

Increasing access to fresh air, either through indoor ventilation or more time spent outside.

Rather than spending money on plexiglass, schools may be better served allocating those resources to improving indoor ventilation. This may mean upgrading or repairing HVAC systems. It could also mean simply repairing windows so that they open safely. Even six inches of opening can generate adequate air exchange in an hour. There are also opportunities to increase access to fresh air that are not dependent on the budget. When weather permits, lunch can be eaten on picnic tables or on a grassy field, provided there is enough space for students to spread out. Classes can be conducted outside as well. Some schools are even setting up tents to create open-air classrooms.

Frequent hand-washing with soap and water (preferable) or hand sanitizer (alternative).

Good hand hygiene is always important, and that’s no different with COVID-19. Students and staff should wash their hands when entering or leaving the school building or classroom, before and after eating, before and after touching their masks or any shared objects or surfaces, after using the bathroom, and after coughing, sneezing, or blowing their noses.

Regularly cleaning high-touch surfaces.

Schools should ensure that frequent cleaning of high-touch surfaces occurs, using EPA approved cleaning spray or wipes. Desks, tables, chairs, counters, bookshelves, and shared spaces should be cleaned once a day or between cohorts of students. Door handles, light switches, handrails, and sink handles should be cleaned every two to four hours and between cohorts. Toys, games, art supplies, instructional materials and manipulatives, tablets, and computers should be cleaned between each use. Eating surfaces should be cleaned before and after each meal.

Staying home when you’re not feeling well.

If a student or staff member is not feeling well, whether they have COVID-19 symptoms or others, it is always best to err on the side of caution and stay home. Staff and families of students should follow the procedures outlined by their school and local board of health, including guidance on testing. If you have questions about whether you qualify or should get a coronavirus test, you can call your primary care team and/or consider calling your local department of health or visiting their website.

Asaf Bitton, MD, MPH, is the executive director of Ariadne Labs in Boston, MA.

Evan Benjamin, MD, MS, FACP, is the Chief Medical Officer at Ariadne Labs, an Associate Professor of Medicine at Harvard Medical School, and an Associate Professor of Health Policy and Management at the Harvard T.H . Chan School of Public Health.

Margaret Ben-Or, MPH, is a project manager at Ariadne Labs.Illustrations by Mimomy / iStock