Confirmed COVID-19 cases are being uncovered in higher numbers in Washington and schools in Kitsap County have backed off bringing students back to school for in-person learning for at least the rest of 2020.

As school and state officials search for ways to get students back to the classroom, a report from the Bellevue-based Institute for Disease Modeling took a look at how effective testing would be in helping to migitate the risk of mass COVID-19 transmission in schools.

Greater testing efforts are underway with a county-operated drive-thru site in Bremerton, another testing site on Bainbridge Island, and the opening of one-day-per-week testing on the campuses of Olympic College in Bremerton and Poulsbo.

The report reaffirms that while there will always be risk in having students return to school, the state’s safety measures, a hybrid schedule and bringing back students in phases starting with the youngest, will go a long way to reduce that risk.

Diagnostic screening and testing for COVID-19 has a place as well, though the effect will be limited, the report says. Testing’s greatest strength is in keeping the virus’s reproduction rate low and in monitoring how much disease activity is happening within a given school.

“These latest results indicate that the benefits of routine diagnostic testing will be limited if COVID-19 prevalence is low and if school-based countermeasures can be fully implemented,” said Dr. Daniel J. Klein, senior research manager at IDM. “Of course, diagnostic testing remains valuable for disease detection and response and for assessing school community prevalence.”

The IDM model anaylzed over three months the difference between five scenarios — full in-person learning without safety measures, full in-person learning with safety measures, hybrid learning, K-5 in-person with other students remote and all-remote learning. The study was done using data from King County, which at the time had a 14-day average of 74 cases per 100,000 residents. Kitsap is currently much higher, with a rate of 102 cases per 100,000 residents.

As expected, the highest infection rates are when schools resume in-person without safety precautions — as high as 45 percent for staff and 33 percent for students. Bi-weekly diagnostic testing would bring those numbers down to 13 percent and 8 percent respectively, and daily testing would reduce numbers even further.

However, that is still considerably higher than the other scenarios. Even a full-time schedule with proper countermeasures brings the attack rate down to just above 2 percent for staff and below 2 percent for students. Diagnostic testing can bring those numbers down even further.

However, with safety measures in place, testing can help keep the reproductive number below one, meaning the virus would not spread.

Klein said that virus in schools would tend to mirror the community and that in-person learning with proper safety measures does not dramatically increase community-wide virus transmission.

“When we are in a status where we’re seeing a rise in cases, that’s not the ideal time to be expanding learning,” said Lacy Fehrenbach, the state’s deputy health secretary. “The good news is, when we’ve looked across the country, we have seen many schools and districts with rates higher than what we see in Washington that have brought back kids for in-person learning.”

State officials believe the robust safety measures in place, which all schools, public and private, must follow, are effective in keeping transmission low. Some of the measures include daily monitoring and health screening, masks, 6 feet of distance between students whenever possible, increased hand hygiene, and testing and tracing to isolate confirmed cases.

“These safety measures we have outlined for all schools to follow in Washington appear to be very effective,” state health officer Dr. Kathy Lofy said.

Fehrenbach said that the risk for younger students appears to be much lower, in that they seem to be less suspectible to COVID-19 than the rest of the population and are less likely to transmit it, while infection rates among staff generally reflects the community.

Although local public health districts mainly collect data on school outbreaks, Fehrenbach said 42 outbreaks have been reported to the state thus far. However, an outbreak is simply defined as two or more cases with an epidemiological link. Only between 1 and 3 percent of those outbreaks have involved five cases or more.

“We are fortunately not seeing the large outbreaks many of us might have feared with the return to school,” Fehrenbach said.

The full IDM report can be found here.