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Colorado schools are set to open in a few weeks. The state hasn’t modeled the impact.

Second graders stand in a circle for a game in Kari Notton's class at Carson Elementary, March 13, 2020.
Second graders stand in a circle for a game in Kari Notton’s class at Carson Elementary, March 13, 2020.
Kevin J. Beaty/Denverite

Colorado school districts are planning for the start of the school year as new COVID cases increase around the state. On Tuesday, the head of Colorado’s public health department said the state’s “early warning system has begun to blink red.”

How opening school to roughly 860,000 students around the state might affect the trajectory of the coronavirus in Colorado remains an open question. The model developed by the Colorado School of Public Health, which the state relies on, doesn’t include schools in its assumptions. Other countries that opened schools successfully did not do so when cases were rising.

“You can think of social distancing as a percent reduction in people’s normal contact rates,” said Elizabeth Carlton, an assistant professor at the Colorado School of Public Health at University of Colorado Anschutz and a member of the modeling team, in an email.

“We expect the contact rate to increase for certain populations if schools open, but have not modeled that directly,” she wrote. “In general, transmission increases as contact rates increase (or social distancing decreases) but there are open questions about how well kids transmit infections.”

Current projections show intensive care units in Colorado hospitals reaching capacity by some time in September. In an effort to change that trajectory, Gov. Jared Polis has closed bars and issued a statewide mask mandate. It will take weeks to see the effect of these changes, just as it took weeks for the impact of reopening and more social contact to show up first as an increase in cases and now as an increase in hospitalizations.

However, the state’s model predicts that masks alone won’t be enough to change the trajectory. People still need to gather less and distance more, the Denver Post reported Saturday.

“What is at stake is our children’s ability to head back to the classroom, where their education is better served,” Jill Hunsaker Ryan, executive director of the Colorado Department of Public Health Environment said in a press conference as she urged people to wear masks and stay home when possible. “We’re at a critical juncture in allowing that to happen.”

Opening schools inevitably will lead people to leave their homes and interact more with others, both within school buildings and as more parents return to work. There is some evidence that younger children transmit the virus less easily than teenagers and adults, so the effect on transmission rates likely would be less than if a similar number of adults were interacting with each other in close quarters every day. At the same time, a recent study found that children older than 10 transmit the virus as easily as adults do.

Because widespread school closures in the spring were accompanied by the closure of most other businesses and a broader stay-at-home order, it’s hard to isolate the impact of any one action.

Brian Castrucci of the de Beaumont Foundation, which works on public health issues, said that schools that open to in-person learning are essentially running “a giant transmission experiment” on children.

“We’ll know in three or four months,” he said.

Internationally, many countries that successfully returned to school have had smaller class sizes and more distancing. Israel, which had a more normal return to school, quickly saw outbreaks in school buildings.

In announcing new state guidance for schools that allows normal class sizes for elementary students, Brian Erly, a medical epidemiologist with the Colorado Department of Public Health and Environment, pointed to the experience of Sweden, which kept schools open for elementary and middle school students with very few changes along with allowing most businesses to continue operating.

Sweden saw many more fatalities than its Scandinavian neighbors but had similarly low rates of hospitalization for children under 18, despite keeping schools open. While Erly said Colorado shouldn’t follow Sweden’s approach in general, the outcome suggests schools didn’t drive spread in the community.

But the magazine Science reported that Sweden did little research, testing, or contact tracing when schools had outbreaks, even when teachers and staff died.

“It’s really frustrating that we haven’t been able to answer some relatively basic questions on transmission and the role of different interventions,” Carina King, an infectious disease epidemiologist at the Karolinska Institute, Sweden’s flagship medical research center, told Science.

The rate of community transmission, meanwhile, is weighing on the decision to open school to in-person classes. One factor cited by Denver Superintendent Susana Cordova in waiting to bring students back to school buildings was the growing rate of COVID in the community. Aurora Superintendent Rico Munn has proposed making a decision about starting remotely based on public health data in early August.

Bill Burman, the head of Denver Public Health, said in an email that the increase in cases would make it harder to keep COVID out of school buildings. He also noted that countries that successfully brought students back to classrooms did not have rising rates in the community.

Burman has been an advocate for opening schools, but doing that well also depends on adequate testing, quick test results, and keeping overall cases down, he said.

“One concern at present is the relatively high and rising rates of community transmission, particularly among young adults (who are likely to be around children),” he wrote. “These rates mean that students and staff will have significant risks of COVID exposure outside of school and that classes may be disrupted by relatively frequent quarantine in response to community-acquired COVID cases.”

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