Staff photo by Troy Stolt / Tonya Schuman and Rachel Tripp conduct a coronavirus test at a COVID-19 testing site put on by CEMPA and La Paz on Thursday, July 30, 2020 in Chattanooga, Tenn.

High demand for coronavirus tests is making test results take longer and at times forcing the Hamilton County Health Department to turn people away from its drive-thru testing site, according to the county's top public health official.

Becky Barnes, Hamilton County Health Department administrator, said it's now taking on average four to six days to get COVID-19 test results in the county, whereas it had been taking 48 to 72 hours.

"Many laboratories in the state are experiencing an increase in turnaround time at the laboratory level, leading to longer times between specimens being collected and results being reported to us and the state," Barnes said via email Friday.

She also cited issues with demand for testing at the county's Alstom testing site, 1125 Riverfront Parkway.

"There have been days just recently when we had to stop any additions to the Alstom testing line because cars were backed up too far in the road," she said.

Barnes said another issue is that the Tennessee Department of Health recently upgraded its electronic disease surveillance system, causing an increase in the amount of time it takes to process incoming labs and leading to a backlog of both positive and negative results being imported into the system.

Hamilton County is averaging 180 new COVID-19 cases a day in the past week after the fourth straight day of more than 200 new infections reported by the health department.

Health department investigations show that many of the new infections are occurring within households, according to a news release from the health department.

"Typically, a household member becomes infected outside of the home, such as in a workplace or social gathering, and then brings the virus home and infects others living there. These household infections occur quickly, and both adults and children can spread the virus," the news release states.

In the release, Barnes said that "some people with COVID-19 show no or mild symptoms and think they can go on about their normal routines, but this is contributing to the spike in cases. Anyone testing positive, whether they have symptoms or not, needs to isolate both from the community and within the home."

As of Friday, there were 113 confirmed coronavirus patients hospitalized in the county and nine probable patients, including 53 Hamilton County residents and 35 patients in intensive care.

Two more Hamilton County residents have died due to COVID-19, for a total of 122 deaths since March.

Contact Elizabeth Fite at or follow her on Twitter @ecfite.