COVID-19 in Hamilton County, TN

Latest Count

Recent Deaths

Vaccine coverage

Vaccination Data

Percentage of total population of Hamilton County residents reported to have received at least the first dose of Covid-19 vaccine. Source: TDH

About the data

Sources: Hamilton County Health Department (cases, deaths, hospitalized, case positivity rate, epi-linked cases), Tennessee Department of Health (test results, test positivity rate)Update schedule: HCHD updates are made between 15:00-16:00 Eastern. TDH updates are made at 18:00 Eastern. Cases, deaths, test results, and test positivity rate are updated daily. Hospitalized, case positivity rate, and epi-linked cases are not updated on weekends or holidays.Population: All metrics reflect only Hamilton County residents with the exception of hospitalized and hospitalized in ICU, which include non-Hamilton County residents hospitalized within the county.Cases include confirmed (PCR+) and probable casesTest positivity rate is calculated over a 7-day period: (Sum of PCR+ in last 7 days) / (Sum of PCR test results in last 7 days).Case positivity rate is calculated over a 7-day period: (Sum of cases in last 7 days) / (Sum of PCR- in last 7 days + Sum of cases in last 7 days).Epi-linked cases is calculated over a 7-day period: (Sum of epi-linked cases in last 7 days) / (Sum of cases in last 7 days). A case is considered epidemiologically linked if the transmission of the virus can be linked to a laboratory confirmed positive case.Vaccine recipients include Hamilton County residents reported to have received at least the first dose of Covid-19 vaccine. Includes vaccines administered by all providers. Denominator for calculating percentage vaccinated is total county population.14-day change trends use 7-day averages; all are % change except for test positivity rate (absolute change).Age demographics are not reported on weekends or holidays. On days following weekends and holidays, newly reported deaths shown here are cumulative over the reporting period.Risk levels and criteria are derived from Harvard Global Health Institute Key Metrics for COVID Suppression unified framework and CovidActNow.

Cases

This chart shows new reported cases among Hamilton County residents (light red bars) and the 7-day simple moving average (red line). Color coded risk levels apply to the moving average line and are derived from Harvard Global Health Institute Key Metrics Framework. On 18 Aug 2020, the HCHD added 90 historical probable cases to the total number of cases (press release). On 14 Nov 2020 and 16-19 Nov 2020, HCHD's case count was incomplete due to technical difficulties with data reporting systems. On 26-27 Nov 2020, HCHD did not report cases due the the Thanksgiving holiday. Source: HCHD

Deaths

This chart shows new deaths by date of death among Hamilton County residents (grey bars) and the 7-day simple moving average (black line). Note that there is a lag in deaths reporting; to account for some of this, the 7-day average is not shown for the most recent 10 days. Source: TDH

Hospitalizations

This stacked area chart shows the contribution of each inpatient category to the total number of hospitalized individuals on each day and includes non-Hamilton County residents who are hospitalized in Hamilton County. Persons under investigation are individuals who are/were under investigation for having COVID-19 on the reporting day. Reporting of cases hospitalized began on 26 Mar 2020. Reporting of hospitalized persons under investigation began on 29 Mar 2020. Reporting of cases hospitalized in ICUs began on 16 Apr 2020. Data was not reported on 28 Apr 2020 or 18 Mar 2020. Source: HCHD

Hamilton County hospitals serve a number of surrounding counties. This overlaid area chart shows the contribution of Hamilton County residents and non-Hamilton County residents to the number of hospitalized cases (combined cases and persons under investigation) on each day (7-day average). Reporting of residents and non-residents began on 4 June. Source: HCHD

Testing

This chart shows daily new tests and the 7-day simple moving average. Because HCHD does not report positive test results, TDH data is used. Source: TDH

This line chart shows the test positivity rate by day, calculated over a 7-day period: (Sum of PCR+ in last 7 days) / (Sum of PCR test results in last 7 days). HCHD does not report positive PCR test results or total PCR test results, so TDH data is used. Color coded risk levels are derived from Harvard Global Health Institute Key Metrics Framework and CovidActNow. Source: TDH

Contact Tracing

This chart shows the performance of the contact tracing program as a percentage of new cases in the last 7 days that are epi-linked. A case is considered epidemiologically linked, or epi-linked, if the transmission of the virus can be linked to a laboratory confirmed positive case. Mitigation and Suppression Goals are derived from Harvard Global Health Institute Key Metrics Framework. The goal for a mitigation strategy is to stay above 50%; the goal for a suppression strategy is to stay above the 80%. Source: HCHD

Wastewater

This chart shows a comparison of normalized SARS-CoV-2 concentration in wastewater and new cases per 100K people (7-day simple moving average) by specimen collection date. Wastewater samples are collected at the Moccasin Bend Wastewater Treatment Plant—every two weeks though April 2021, then twice per week beginning in May 2021. SARS-CoV-2 viral concentration is directly measured by laboratory RT-qPCR assay. To account for differences in dilution, the raw SARS-CoV-2 viral concentration is normalized to a fecal indicator. PMMV is used as this fecal indicator, which is an RNA virus that is commonly excreted in stool. Sources: TDH, City of Chattanooga, BioBot

Metrics Framework

From Harvard Global Health Institute Key Metrics Framework

About Hamilton County Health Department data

Data gaps and other irregularities

On 14, 16-19 Nov 2020, HCHD's daily case count was incomplete due to technical difficulties with data reporting systems.
On 26-27 Nov 2020, HCHD did not report cases or deaths due to the Thanksgiving holiday.

Probable Cases

On 18 Aug 2020, the HCHD added 90 historical probable cases to the total number of cases due to a "data catch up" (press release). No information was provided about how recent the historical probable cases were, or if those individuals were ever tested. They indicated that probable cases have been included in the total number of cases since late June.
HCHD does not stratify public case data into lab-confirmed cases and probable cases. However, TDH does stratify cases in this way in their public dataset.

Total Test Results

On 22 Jul 2020, the HCHD stopped reporting total test results data.

Negative Test Results

On 22 Jul 2020, the HCHD stopped reporting negative test results data, indicating they were "in the process of cleaning the data to eliminate duplicates and out of county/state labs."
On 24 Jul 2020, the HCHD indicated that "on July 21 the state’s database system was unavailable producing an inaccurate daily total of negative PCR tests for Hamilton County." They also indicated that negative test results data were incomplete due to a pending data merge. The estimated time to complete the merge was given as 10-14 days.
On 14 Aug 2020, calculations indicate that HCHD over-counted total negative test results by 10 (compare to data on 13 August). There was no indication that this was due to a correction in historical data or a result of the data merge.
On 18 Aug 2020, the estimated time of completion for the data merge was revised to "an additional few weeks."

Positive Test Results

On 18 Aug 2020, the HCHD stopped reporting positive test results data.
Total positive tests were equivalent to total cases on all days they were both reported (weekdays, except holidays). Because the HCHD indicated they were including probable cases in the total cases data since late June, this calls into question the accuracy of the positive test results data from that point forward.

Implications

The key metrics that measure case incidence are affected:

Daily Cases
Daily Cases per 100,000 people (7 day average)
The two key metrics that measure testing capacity and performance are affected:
Daily New Test Results - therefore, the data presented in the visualizations here are from Tennessee Department of Health
Daily Test Positivity Rate - therefore, the data presented in the visualizations here are from Tennessee Department of Health

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