NASHVILLE, Tenn. (WKRN) — One of the most frequently asked questions during the COVID-19 pandemic is why the number of confirmed cases by the Tennessee Health Department differs from some of the reports from county health officials.

The county with the biggest difference in reported cases is Davidson. Each day the Metro Public Health Department releases its confirmed cases update at 9:30 a.m. Over the last few days, the number of cases they announce is considerably different than what the Tennessee Department of Health lists in its daily 2 p.m. update.

Date MPHD CasesTDH CasesDifference
3/2318416420 cases
3/2425318370 cases
3/2525718869 cases
3/2629320390 cases

The difference in reported cases reached nearly 100 on Thursday when Metro Public Health officials announced Davidson County had reached 293 cases, while the Tennessee Department of Health reported 203 confirmed cases later in the day.

During a statewide teleconference on March 24, Tennessee Department of Health Commissioner Dr. Lisa Piercey noted differences between state numbers and the reported numbers from local agencies, reaffirming that existing verification processes lead to some delay in the state’s reporting of numbers.

Later that day, the Tennessee Department of Health released a statement to further clarify differences in reported cases.

We are sharing case numbers once a day, at 2 p.m. CDT, and the numbers we share on our website reflect all cases of which we’ve been notified at the time they are posted. The laboratory results of positive cases are reported first to the local health departments and are given to them as soon as results are available so they can follow up with those patients. Those notifications are happening throughout the day, so in some cases, county health departments such as the Metro Public Health Department will get information before we do. They decide when and how frequently they are sharing case numbers for their jurisdiction.

In Memphis, Shelby County Health officials said there is a “lag” in receiving results from the state. Part of the reason for the delay is the increasing amount of testing sites available to the public.

The Shelby County Health Department releases its latest numbers each afternoon, usually around the same 2 p.m. window the state’s health department releases its daily update. In the most recent reports (March 26) Shelby County officials reported 198 confirmed cases. Tennessee Department of Health’s Thursday update listed the county at 147 cases, a difference of 51 cases.

Over in East Tennessee, the Hamilton County Health Department has reported higher numbers in its afternoon updates, compared to what the state lists. The department’s website states the following:

In the case of a discrepancy between the two websites, our local data should be considered the most up-to-date for Hamilton County. 

The Tennessee Department of Health’s website lists the following disclaimer under testing results:

*Please note, these data are meant to provide a rough estimate of testing volume. Due to different source data, numbers may differ slightly from day to day.

The site also includes a note regarding case counts.

This data changes rapidly as labs conduct tests and identify new cases. Labs assign those cases to a county or leave that information blank. Metro and regional health departments then determine the appropriate county of jurisdiction during their public health investigation. We’re working to reduce the “pending” number to 0. Contact the local health department for county specific information. Cases among Tennessee residents are counted by their county of residence. Residents of other states who were tested at Tennessee healthcare facilities are counted as “Out of TN”.