The number of active COVID-19 cases reported daily on the Hamilton County Health Department website dropped from 1,505 to 603 on Thursday, raising eyebrows across the county and prompting an explanation from department officials.
Officials say the 902-case decrease was the result of several factors, including a downward trend in new reported cases and a "data clean-up" of cases that were no longer active but had failed to automatically roll off the active case list in the standard 14-day period.
"The Health Department applied a 'data clean-up' because some recovered/inactive cases had not rolled off automatically as they were supposed to. Cases were manually removed that were no longer active. Moving forward, this should not be a problem with cases not rolling off timely," according to a news release issued by the health department on Friday.
Another factor contributing to the dramatic decline in cases was that the department "changed the automatic roll-off of 'active' status from 21 days to 14 days earlier this month to align with Tennessee Department of Health and [federal] guidance," the release states.
Active cases are the number of people who've tested positive for the coronavirus still in their infectious period, which is typically 10 days, but can be longer.
"The Health Department uses a 14-day period to account for some of these variables. An estimate of active cases can be the cumulative number of cases for the past ten days. The exact number that is reported will reflect variables such as how early in their infectious period cases were reported and cases with prolonged infectious periods," according to the news release.
The number of active coronavirus cases is an important metric used to gauge the severity of the local outbreak. It's one of the data points Hamilton County Schools uses to decide whether or not to stay or change to a different phase of the district's reopening plan.
As of Friday afternoon, the health department reported 615 active cases and 8,833 total inactive, or recovered cases, since the start of the pandemic.
Two new COVID-19 deaths were reported Friday, for a total of 94, and 52 coronavirus patients were hospitalized in the county. Of those hospitalized, 25 were residents of Hamilton County and 18 were in intensive care.
COVID-19 data for Hamilton County is updated daily on the health department's website between 3 and 4 p.m.
Contact Elizabeth Fite at firstname.lastname@example.org or follow her on Twitter @ecfite.