Central District Health Simplifies School Category Determinations for Weekly Reporting

Tuesday, September 15, 2020

Central District Health (CDH) has established new metrics for determining weekly school operation categories in Ada, Boise, Elmore, and Valley Counties. The new system will keep Red, Yellow and Green color categories and recommended level of operations, but will entirely replace the previous category definitions with average case rates calculated for each county. CDH will use a two-week average of daily COVID-19 cases calculated per 100,000 people in a given county. The new system is aimed at simplifying the way categories for schools are determined within CDH’s four-county jurisdiction.

“We recognize that the weekly category determinations we make are weighed heavily by the schools in our communities when making their decisions, and we take that responsibility very seriously. We want the public to have a good grasp on why and how these decisions are being made within CDH and to be able to look at the data and understand what it takes to move between the three categories,” said Russ Duke, District Director for CDH.

Possible Differences for Rural Communities CDH recognizes the potential for community spread differences within its rural counties of Boise, Elmore, and Valley, and the role that geographic distance might play in a community’s risk. For instance, Basin School District and Horseshoe Bend School District are both located in Boise County, but are approximately 30 miles apart and an hour’s drive. Because of the significant geographic distance, it is possible that two school districts within the same county could, at times, be in different risk categories. CDH will work directly with the school districts and independent schools if this situation arises.

Red, Yellow, Green Criteria by County Determined by a two week average daily rate calculation. Please see the end of this news release for an example of how average case rates are calculated.

Ada and Elmore Counties

Red = Case rate of 20.0 or greater

Yellow= Case rate greater than 3.0 but less than 20.0

Green= Case rate of 3.0 or less

Boise and Valley Counties

Red = Case rate of 30.0 or greater

Yellow= Case rate greater than 5.0 but less than 30.0

Green= Case rate of 5.0 or less

Corresponding data will be posted on Mondays and Thursdays by noon to CDH’s Tableau data site and CDH will continue to update its School Categories webpage each Monday (excluding holidays) at https://www.cdh.idaho.gov/dac-coronavirus-schools.php. Category reporting with the new metrics began on Tuesday, September 8 due to the Labor Day holiday on Monday.

Case Rate Calculation Example:

If 80 cases were reported over 14 days in Elmore County

Step 1: Calculate Average Cases Per Day: 80 cases ÷14 days = 5.71 average cases per day

Step 2: Convert to Case Rate: 5.71 ÷ 27,511 (Elmore Co Population) = 0.0002075 cases per person in county

Step 3: Convert Case Rate to per 100,000: 0.0002075 x 100,000= 20.75 cases per 100,000 population

= 20.75 for the 2-week average rate / Red Category ** SAMPLE CALCULATION