IDM report outlines measures schools could take to reopen

A new report from the Institute for Disease Modeling (IDM), released by the state Department of Health, supports the recommendation that in-person learning isn’t wise if community transmission rates of COVID-19 are high.

The report also explains how diagnostic screening situations could help mitigate risk associated with reopening schools. While risks still exist, they could be reduced through countermeasures, hybrid scheduling, and phasing in grades K-5 first.

The report’s findings include:
1. If schools can implement countermeasures consistently and community transmission is low, then the value of testing people for COVID-19 is limited. The analysis looked at several different testing strategies using PCR tests and rapid antigen tests, both individually and in combination.

2. Consistent with previous analyses, transmission in schools is greatly reduced through a combination of school-based countermeasures and hybrid or phased-in scheduling. Routine diagnostic screening of asymptomatic people can, however, have an impact on reducing transmission if schools are a significant source of infection. Daily symptom screening followed by diagnostic testing and contact tracing remain important along with other countermeasures.

3. The number of in-person days lost compared to a typical 5-day school week is largely due to scheduling, not people staying home to quarantine or isolate. Frequent screening with antigen tests does slightly increase in-person days lost, but less than 5% of days lost are due to health concerns, including false-positive diagnostic screening results.

4. The report also reaffirms the importance of reducing community transmission prior to reopening K-12 schools for in-person learning and implementing school-based countermeasures. Countermeasures include masking, cohorting students, daily symptom screening, follow-up diagnostic testing, contact tracing, physical distancing, hand hygiene, and improved ventilation. Without countermeasures, up to 45% of teachers and staff and 33% of students could become infected in the first three months; countermeasures reduce this risk to less than 2%, even with a full schedule of five days of in-person classes.

The IDM report also includes “what-if” scenarios and found that risks might be higher if it’s found that young children are equally susceptible as adults to infection from the virus, if community transmission increases after schools reopen (possibly if parents also return to work), and daily screening isn’t implemented or effective.

The report concluded that it’s wise not to reopen schools for in-person learning if rates of transmission are high.

“The findings of this modeling indicate that it is possible to carefully resume some in-person learning for some students, especially younger students, while keeping the risk of transmission in our schools relatively low if strong health and safety measures are in place,” said Lacy Fehrenbach, deputy secretary for COVID-19 response at DOH.

Ultimately, state health experts agree that the behavior of every single Washingtonian — even those who don’t spend time around kids — will affect whether or not schools can reopen. It is our actions that determine how fast coronavirus is spreading in communities around the state.

“What the future looks like a few weeks from now and in January depends entirely on what each one of us chooses to do today and in the next few weeks,” Fehrenbach said. “We all have to double-down our efforts to wear our masks, watch our distance, and really think carefully about our social gatherings.”

State Health Officer Dr. Kathy Lofy pointed to a recent study from Western Washington University that found only half of people wear a mask when having people outside the household over to the home.

“We now have good data that shows that people are really good about wearing masks when they go to the grocery store or the pharmacy or on an errand,” Lofy said. “Where we are not so good is when we have a friend over or have a meal with a friend in our house.”

She said we need to keep those gatherings small and masked if we want transmission to be low enough for schools to reopen.

“We really think that [those at-home gatherings] are where a lot of the transmission is happening,” Lofy said. “So we all need to commit to this. We’ve bent the curve [before], and I’m really confident that we can do it again.”

KIRO Radio’s Nicole Jennings contributed to this report.

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