Hamilton County Schools Reopening: A Case Incidence Analysis

10 August 2020 (updated with latest TDH data as of 15:15 ET 27 Sep 2020)

How many cases can we expect to see in Hamilton County Schools as students return to school? Let’s walk through the analysis.

New Daily Cases

The Tennessee Department of Health publishes daily case data by county for the 5-18 year age range.

Data source: Tennessee Department of Health

Population

According to the US Census Bureau 2018 ACS 1-Year estimate, there are 64,700 people living in Hamilton County in the 5-19 age range.

## Age 5-9 Population

21,253

## Age 10-14 Population

21,151

## Age 15-19 Population

22,296

## Age 5-19 Population

21,253 + 21,151 + 22,296 = 64,700

We can adjust this to only include ages 5-18 by estimating the number of people who are age 19 and subtracting that from the total.

## Age 19 Population Estimate

22,296 / 5 = 4,459

That results in an estimate of 60,241 children in the 5-18 age range.

## Age 5-18 Population Estimate

64,700 - 4,459 = 60,241

Weekly Case Incidence Rate

As of 27 September, the number of cases in the last 7 days in children age 5-18 in Hamilton County was 60. That’s 0.0996% of that age group population.

## Weekly Case Incidence Rate for Age 5-18 Population

60 / 60,241 = 0.000996

Weekly Case Incidence for proportion of in-person students

Let’s apply that case incidence rate (cases in the last 7 days per population) to the number of children returning to in-person classes.

According to the Tennessee Department of Education, Hamilton County Schools enrolled 44,376 students in the 2018-2019 school year. The Times Free Press reports that at least 30% of students will be utilizing an online learning option. Because we don't have an exact percentage, let's choose a conservative value and say that 65% will be attending school in person—that’s 28,844 students.

## In-person Students Population Estimate

0.65 * 44,376 = 28,844

Multiply the calculated 7-day case incidence rate (0.0996%) by the number of in-person students (28,844), and the result is 29 new cases over 7 days.

## Weekly Case Incidence for Estimated In-person Student Population

0.000996 * 28,844 = 28.73

Note that this does not take into account:

  • future changes in case incidence among students. This is important because as school reopens, there will be a major change in social interaction and environmental conditions amongst students.

  • changes in the testing rate among students attending in-person classes.

  • cases amongst the 3,727 teachers, staff, and administrators.