Joseph G. Allen is an associate professor and director of the Healthy Buildings program at Harvard University’s T.H. Chan School of Public Health. Helen Jenkins is an associate professor of biostatistics at Boston University School of Public Health.

The new report on schools from the Centers for Disease Control and Prevention should be a wake-up call to parents everywhere: If they’re not back already, your kids are not going back to school full-time this year.

The report adds new and unnecessary demands that will ultimately keep millions of kids out of school. In particular, there are two items that will act as barriers: the use of community-spread metrics to determine whether schools should open, and the requirement of routine screening testing.

The CDC defines four color-coded levels of the spread of covid-19 in a school’s surrounding community: blue (low), yellow (moderate), orange (substantial) and red (high). If community spread is red and if schools don’t have routine screening testing in place, two conditions that exist in more than 90 percent of the country right now, the CDC recommends closing middle and high schools, unless all mitigation strategies can be strictly adhered to, and hybrid models for young learners. If it is orange, middle schools and high schools join elementary schools in being able to go hybrid. In yellow or blue communities, all K-12 schools can be open for in-person instruction.

But community-spread metrics pose major problems. We’re part of a group of faculty and researchers at Harvard, Boston University and Brown University that released a report in July using such metrics as indicators for when to open schools. We changed our position on this in light of overwhelming scientific evidence that transmission within schools can be kept low regardless of community spread, so long as good mitigation measures are in place. It’s also clear that community spread is not an indicator of within-school transmission. The CDC itself released a study showing this. It also recently wrote that there is “little evidence that schools have contributed meaningfully to community transmission.” So why tie reopening schools to community spread?

There’s another problem with the two community-spread metrics selected — cases per 100,000 people in the last seven days, and the percentage of covid-19 tests that are positive. The first metric is entirely dependent on how much a community is testing; the second is flawed because it cannot be interpreted without understanding who is being targeted for testing.

The thresholds for these metrics are also very low. Communities only get into the blue zone if they report about one daily case per 100,000. Good luck to any districts hoping to get to that level before most people are vaccinated. And when a district eventually does move into the blue or yellow zone, the CDC wrote that this should be “documented continuously for several weeks” before transitioning to full in-person teaching, further adding delay to any potential reopening.

Remarkably, even if schools implement screening testing — defined as testing teachers at least weekly and offering a few different student testing strategies — the CDC still recommends hybrid models for schools in red- and orange-level communities. So if such a school did take on screening testing, all that would get them is moving middle and high schools into a hybrid model. That’s a big lift for not much gain toward reopening.

There are other issues with the report: The CDC is right to require masks in schools. Ideally, though, they would have specified high-efficiency masks or double-masking for adults.

The blanket ban on sports in red-zone communities lacks nuance. Many sports can be played safely outdoors with good controls in place, even if community spread is high. This has a similar feel to the widely panned and draconian approach taken at the University of California at Berkeley to ban all outside activities, including working alone.

The CDC emphasizes hand-washing, which is great, but it overemphasizes cleaning. There isn’t a single documented case of covid-19 transmission through surfaces, so why is the CDC emphasizing things such as cleaning outdoor playground equipment that have no bearing on exposure or risk? Shared air is the problem, not shared surfaces.

On that point, the CDC gives lip service to ventilation, but you have to get to page 13 to find it under the last bullet under “Cleaning and maintaining healthy facilities.” The CDC recognizes airborne transmission of covid-19, so why is ventilation not more prominent?

Finally, the CDC emphasizes maintaining six feet of distancing, even between kids. But that ignores the science on children, transmission and the power of layered risk-reduction measures. One of us (Allen) and another colleague have recommended three feet of distancing for kid-kid interaction while keeping adults six feet from everyone else. Why? Because with masks, distancing is important, but not the key factor determining risk. As an example, hospitals don’t distance at all. Ultimately, this six-foot distancing rule is what will keep most kids out of school simply because of space limitations.

The science is clear: Kids — especially young children — can get and transmit covid-19, but they are less likely to do so than adults. Kids can die from the disease, but the risk of that happening is one in a million; they are about 10 times as likely to die by suicide. Teachers also have lower risk than other occupations and can be kept safe through adherence to universal precautions.

The science is also clear that keeping children out of school is doing real harm: Loss in literacy progress. An exploding mental health crisis. Billions of missed meals. Women dropping out of the workforce. Hundreds of thousands of kids missing school. The effects are compounding daily.

We’re all for stringent controls in schools. There are many that are both effective for adults and kids and don’t keep kids out of school, as some of these new ones from CDC will. At some point, we have to recognize the consequences of keeping millions out of school for a year and treat this like the national emergency it is.

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