Mapping the Outbreak

Mapping the Outbreak

Health Department data shows the pattern of the coronavirus outbreak in Knox County and could indicate where testing is lacking.

by scott barker • April 15, 2020
Covid-19 case distribution map (Knox County Health Department image).

Most of Knox County’s COVID-19 patients live within an arc running from Raccoon Valley in the north through Farragut and West Knoxville to Kimberlin Heights in the south, according to a map released by the Knox County Health Department. 

The Health Department publishes case data based on where patients live, not where they might have been exposed to the novel coronavirus.

Using data of COVID-19 cases through last Friday, the Health Department’s map depicts the distribution of positive test results for 154 cases by ZIP Code, though 39 aren’t shown in any particular location. 

Dr. Martha Buchanan, director of the Knox County Health Department, said the map shows a pattern of positive results but could look different if testing were more widespread.

“When we look at the map, we do see concentrations in certain ZIP Codes,” Buchanan said during a media briefing on Monday. “What we don’t know is testing availability throughout the county in the other ZIP Codes.”

The cases were all those that had a symptom onset date of April 4 or before, and a positive test result as of last Friday, April 10, Buchanan said. Knox County had reported a total of 154 presumed positive cases on that date.

The map shows 103 cases in a semi-circle of nine contiguous ZIP Codes north, west and south of the downtown Knoxville area. A dozen other identified cases are in North Knoxville. 

The remaining 39 cases are scattered among 11 other ZIP Codes, which encompass Downtown, Northwest Knoxville, Fountain City and East Knox County. The Health Department only noted that each of those ZIP Codes are seeing 0-5 cases each.

Numbers weren’t given for ZIP Codes with five or fewer cases because the Health Department has concerns about protecting the privacy of patients when only a few have tested positive within a small area, Buchanan said.

“Anecdotally, in other jurisdictions people have actually had threats to their lives or their children have been bullied,” she said. “People have lost their jobs when they’ve been identified as a case of COVID-19.”

The ZIP Codes with the most COVID-19 cases, according to the data, are 37919 (Sequoyah Hills, Bearden, Lyons Bend) with 18, 37923 (Cedar Bluff) with 16 and 37922 (Bluegrass) with 14. 

Hardin Valley (37932), Concord/Farragut (37934), South Knoxville and South Knox County (37920), and North Knoxville south of Interstate-640 (37917) had 12 cases each.

County Commission Chairman Hugh Nystrom, who represents just about all of the 37919 ZIP Code that includes Sequoyah Hills and Lyons Bend, said he’s grateful the Health Department is providing more localized data.

“Seeing the case count in my own West Knoxville backyard is concerning,” he said. “I know that as we continue to expand testing it will help provide a much better understanding of the burden of the disease in our community." 

Health Department case data is based on the address of the patient who has tested positive, not where they might have been exposed to the coronavirus. A person who lives in Farragut, for example, but contracted the coronavirus at work or at social events in Knoxville, Oak Ridge or Maryville, would be listed as a Farragut case.

“This map underscores the eminent need for all Knoxville citizens, including District 2 residents, to be vigilant about staying home and reducing unnecessary trips,” said City Councilman Andrew Roberto, who represents West Knoxville.

Last week, the Health Department’s top epidemiologist, Roberta Sturm, told Compass that diseases don’t respect borders. She was referring to intercounty spread, but ZIP Code boundaries are just as arbitrary as county lines.

One example can be found in West Knoxville. West Hills, which has 0-5 cases, is in ZIP Code 37909 on the other side of Interstate-40 from ZIP Code 37919, which has 18 cases.   

West Knoxville is home to some of the city’s most affluent neighborhoods, with residents having higher income levels and lower poverty rates than the city as a whole. Roberto ventured that access to affordable healthcare and testing among West Knoxvillians could have had an impact on the results.

According to Buchanan, more testing will give public health officials a better idea of the impact of the coronavirus in all Knox County’s communities. As of Tuesday morning, 4,307 people had been tested in Knox County.

The Health Department has been testing people without health insurance for the coronavirus as long as they meet the testing criteria. The criteria have been adjusted in recent days to include more qualifying symptoms and to include people who are in groups at high risk for COVID-19 complications, such as seniors. 

The Health Department now has the capacity to test about 90 people per day. Physicians’ offices and medical clinics also offer tests to patients.

“Continuing to expand testing will help us understand the burden of disease in our community,” she said. “Unfortunately, access to care was an issue before the pandemic and remains an issue to this day.”

Roberto noted that nearly half the confirmed cases in Knox County — 46.45 percent — involve patients under the age of 40. 

“This statistic underscores that this is a rapidly changing pandemic event and the best thing we can do is stay home,” he said. “I urge Knoxville residents to be thoughtful about leaving their homes and reduce trips whenever possible. If you must leave home for an essential trip, please follow CDC guidelines and wear a mask.”

Nystrom also emphasized the importance of following guidelines from the Centers for Disease Control and Prevention to wear masks in public.

“Regardless of what part of Knox County you live in,” he said, “I think it is important for everyone to remain diligent in their commitment to social distancing and following the hygiene protocols.”