Public health guidance: Sullivan County in the green for reopening schools, but data trends toward the red

Local Coronavirus Coverage

SULLIVAN COUNTY, Tenn. (WJHL) – According to the Sullivan County Department of Education’s school reopening plan, Sullivan County Schools would be able to open at normal capacity if opened today, July 10.

July 10 status: Green

According to data from the Tennessee Department of Health, Sullivan County reported 11 new cases of COVID-19 on Friday. That equals 6.95 cases per 100,000 residents, and 4.96 cases per 100,000 people over the past two weeks.

According to the district’s plan, the schools will enter the “yellow” zone of operations at 6 new cases per 100,000 citizens, and will consider a transition to remote learning at 11 new cases per 100,000 residents.

For a comprehensive explanation of these numbers and their significance on Sullivan County Schools’ reopening plan, continue reading.

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According to a district-wide plan released this week, the decision whether to open the doors of Sullivan County schools this fall hinges on one number – 233.

As the school year approaches, if 233 or more Sullivan Countians have tested positive for COVID-19 within the previous 14 days, the county will enter a red zone of “substantial spread” – an average of 16.6 or more new cases daily for the previous two weeks.

That would kick the situation over to a school opening recommendation of “consideration of transition to remote learning” based on the public health framework for reopening Sullivan County is following.

The framework has two other “zones,” a green zone representing no to minimal spread and a yellow zone representing minimal to moderate spread. All are based on the average number of new cases per 100,000 residents using the “14-day rolling average” method.

As of July 9, there were 99 new reported cases of COVID-19 over the past two weeks (4.47 per 100,000 per day), placing it on the high end of the green zone (reopening schools as normal). But the past seven days accounts for 77 of those cases, or 6.96 new cases per 100,000 — near the midpoint of the yellow zone.

In the past three days, the county reported 57 new cases. That’s a three-day rolling average of 12.02 per 100,000 residents — red zone territory.

If the numbers of the past several days are an anomaly, or even the beginning of a short trend, things could be in green territory. If they’re the beginning of a trend with some staying power, school officials will be facing some difficult decisions come late July and early August.

Source: Sullivan County School Reopening plan.

Into the numbers

Based on the plan and data from the Tennessee Department of Health, Sullivan County schools could open under normal circumstances if they opened today. The number of new COVID-19 cases per 100,000 residents averages at 4.47 over the past two weeks, placing it under the threshold of 5 that marks the “green zone” of the plan.

But the data’s trend suggests there are increasing numbers of new cases in Sullivan County that could prevent schools from opening under normal operations.

The plan establishes the framework for the district, which is facing a muddled future shaped by the COVID-19 pandemic.

The conditions for each piece of the framework depend on the number of new cases reported in the county. The plan uses the number of new cases per 100,000 people over the past 14 days as a trigger point to determine in what capacity schools will open this fall.

This number takes into consideration the population of the county while at the same time using a “rolling average” to determine any trends in the data.

The plan reasons that measuring transmission will paint a picture of whether schools can safely reopen.

Scroll to the bottom of this article for a section explaining the methodology used to calculate these numbers.

Based on data from the state health department and calculations by News Channel 11 staff, the metric used to measure how schools will open stands just below the threshold for a normal reopening at 4.47 new cases per 100,000 over the past 14 days, with the threshold at 5 new cases per 100,000 over 14 days.

While that number meets the criteria for a normal reopening, it has been increasing since June 29 from 0.77 to 4.47 in less than two weeks. In one day, the metric increased from 3.70 to 4.47.

To get to the “yellow” zone of the framework, Sullivan County would have to report an average of 9.5 cases per day for 14 days, and to get to the “red” zone, the county would need an average of 17.5 new cases per day for 14 days.

Over the past three days, Sullivan County reported 20, 18 and 19 new cases of COVID-19 for an average of 19 new cases over the past three days. Sullivan County reported an average of 4.3 cases for the three days prior.

According to the plan for Sullivan County schools, the threshold criteria is subject to change in light of new information and additional metrics.


There were several steps involved in the calculations of these numbers. The calculations began by logging the total, cumulative case numbers in Sullivan County from March 10 to July 9, available from the Tennessee Department of Health.

Step 1: Calculating the total number of new cases each day. This value was calculated for a day by subtracting the total number of cases of the previous day. For example, Sullivan County reported 159 cases on July 8, and 141 cases on July 7.

In this case, the formula 159-141=18 shows that there were 18 new cases reported on July 8 in Sullivan County.

The first step is to calculate new cases of COVID-19 each day.

Step 2: Determining the number of new cases per 100,000 residents per day. To determine this value, it’s important to note that the U.S. Census data for 2019 estimates Sullivan County’s population to be 158,348.

To find the number of new cases per 100,000 each day, the formula X*100,000/158,348 was used, with X representing the value calculated in Step 1 for each day.

For July 8, the formula is 18*100,000/158,348=11.37 and shows that there were 11.37 new cases per 100,000 people on July 8.

Step 2 is to determine the new cases per 100,000 people by using the formula X*100,000/Sullivan County’s population (158,348), where X is the number calculated in Step 1 for each day.

Step 3: Determine the moving, or “rolling” average over the past 14 days. The first rolling average was calculated 14 days after the first reported case of COVID-19. The first day was March 10, so the first rolling average is calculated on March 23, and determines the average number of new COVID-19 cases reported from March 10-23.

To maintain the 14-day rolling average, the value on March 24 reflects the average on March 11-24. This is repeated to the latest day.

For July 8, the average is taken from June 25-July 8 to reflect an average of 3.70 new cases per 100,000 people in Sullivan County over the past 14 days.

The final step is to calculate the moving or “rolling” average over the past two weeks.

By these calculations, on July 8, the 14-day average of new COVID-19 cases in Sullivan County was 3.70, and that number increased by almost 3 points in less than two weeks.

News Channel 11 data reporter Jeff Keeling contributed to this report.

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