If King County schools decide to reopen their doors, they should resume in-person classes with elementary students first, according to a new analysis of county demographic and coronavirus data. 

Although young learners are energetic and may struggle to socially distance from each other, elementary schools can more easily separate students into small groups because of the way their days are structured than can middle and high schools. And while the research isn’t settled, younger students may be less susceptible to being infected with the coronavirus. These children are also among the students who are most likely to suffer if they’re learning at home instead of in a classroom.

The research adds heft to recent recommendations made by a major national panel of scientists, and is in line with guidance from Washington education officials who have said schools should prioritize in-person instruction for the state’s youngest learners. A majority of Washington’s students are beginning learning remotely this fall, though some districts and private schools are opting to open buildings.

Even exclusively opening elementary schools carries some danger of coronavirus transmission; no reopening scenario is risk free under the current state of the pandemic, the researchers say.

This story is part of a series about what it’s like to go back to school during a pandemic.

“There really is no ‘no risk’ scenario for resuming in-person schooling in Washington state or really anywhere in the country unless there’s no COVID,” said Jamie Cohen, research scientist at the Bellevue-based Institute for Disease Modeling, who led the study. “If you do resume in-person schooling you can dramatically lower the risk by putting in many of the [infection] counter measures,” such as wearing masks, separating groups of students and enforcing strict screening regimens, such as temperature checks at the door.

The researchers relied on King County school enrollment data to simulate the contact patterns of adults and children within elementary, middle and high schools. They modeled the number of people — children, staff and teachers — who would be expected to walk into schools infected, and possibly seed more infections, from September through November. 

The study doesn’t suggest that any King County schools should open now, or define what level of risk would be acceptable before school buildings reopen. And the findings may not be applicable to the current pace of the pandemic: the model assumes the outbreak is shrinking, but it isn’t clear if that’s the case according to the county’s most recent coronavirus data. IDM works closely with public health officials and its last report, which suggested community-wide efforts must improve significantly for schools to reopen, came out days before a slew of districts announced plans to begin the school year online.

But the findings do lay out predictions for infection rates at schools under various scenarios, such as returning only some students to buildings or using a hybrid model of in-person and remote instruction.

“The real power of the model is to the ability to quickly compare different strategies,” said Dobromir Dimitrov, senior research scientist at Fred Hutchinson Cancer Research Center, who was not involved in the research. Dimitrov and his colleagues are also modeling school reopening strategies and offered similar health recommendations in a recent unpublished study.

School districts may be able to use the predictive modeling method to gauge risks when they begin to consider reopening strategies; IDM might create a risk calculator for schools, but hasn’t finalized these plans.

For instance, the researchers found that if all students returned in-person in September without any safety measures, about 10-25% of teachers and staff and 6-17% of students could be infected with COVID-19 in the first three months. These risks could drop to as low as .3% for adults, and .2% for children if only elementary school students return to school buildings, and these schools use a host of safety precautions, since these children may be less likely to be infected than older peers.

The findings are limited by the fact that researchers are still trying to pin down how the virus operates in children. In their modeling, the researchers assumed children of all ages are less likely than adults to contract it, but once infected, just as likely as adults to infect others. The researchers also weren’t able to model infections based on differences in school sizes: high schools tend to be larger than elementary and middle schools, so it’s possible the study underestimates risk to teens and high school staff and teachers.

Said Dimitrov: “It has a lot of limitations but the overall message and conclusion, I think, are solid.”