For immediate release: November 5, 2020   (20-211)

Contact (press only):  Ginny Streeter, Washington State Department of Health, 360-810-1628Spanish

Kate Davidson, Institute for Disease Modeling, 510-326-4451           

New report explores role of diagnostic testing in school reopening

OLYMPIA – Today, the Washington State Department of Health (DOH) released a new report by the Institute for Disease Modeling (IDM) that quantifies how various diagnostic screening scenarios could help mitigate the risk of COVID-19 transmission associated with reopening schools. The report, the third in a series by IDM, affirms that while there are still risks associated with returning to full in-person instruction, the risks could be significantly reduced through school-based countermeasures, hybrid scheduling, and a phased-in approach that brings back K-5 grades first.

The 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. 

“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, IDM. “Of course, diagnostic testing remains valuable for disease detection and response, and for assessing school community prevalence.”

The report’s authors noted that, as with all modeling, the results depend on assumptions based on the best science and data available. Given the many uncertainties, the report further explores “what-if” scenarios and found that risks may be higher if:

• Young children are found to be equally as susceptible as adults to COVID-19 infection (contrary to current evidence that indicates young children are less susceptible), this could generate a near three-fold increase in the 3-month infection rate. The increase, however, can also be mitigated by fortnightly diagnostic screening.
• Community transmission increases after schools reopen, possibly due to parents and guardians returning to work. 
• Daily symptom screening is not implemented or isn’t as effective as assumed. Diagnostic testing will have more impact if symptom screening is less effective. 

The report supports our guidance that full in-person learning is not wise in places where  COVID-19 transmission levels remain high,” said Lacy Fehrenbach, deputy secretary for COVID-19 response at DOH. “However, 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.

Today, DOH will host a media briefing to discuss the new IDM report. The briefing will include:

Lacy Fehrenbach, MPH, CPH Deputy Secretary of Health for COVID-19 response, DOH.

Kathy Lofy, MD, State Health Officer, DOH

Daniel J. Klein, PhD, Senior Research Manager, IDM

Time: 11:15 a.m. – 12:15 p.m. PST

TVW will livestream the briefing here.

Reporters participating in the Q & A need to register here with name, email, phone and news organization.  TVW will livestream the briefing here.

https://mildep.webex.com/mildep/onstage/g.php?MTID=e8577b84138d8d23b14b5cc56d2cd6365  If you would like to ask a question, you must register and log in to the teleconference via WebEx, and send an e-mail to doh-pio@doh.wa.gov with the subject line “Briefing Question – Schools.

For more COVID-19 data, visit:

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