Almost three-quarters of coronavirus tests done in Tuscaloosa last week appear to be unusable, according to Tuscaloosa Mayor Walt Maddox.

Maddox said late on Friday that more than half of the samples taken at a city testing site since March 16 were “not sufficient or spoiled.” On Monday, Maddox said that number had grown to 723 "unsatisfactory" results of nearly 1,000 samples.

270 returned negative results. 7 returned positives.

More:Coronavirus: More than half of local samples can't be tested, says Tuscaloosa mayor

Unsatisfactory tests could result from a lack of personal information about the patient; a lack of material to test, or improper storage of samples taken. DCH Regional Medical Center, the main hospital in Tuscaloosa, said on its website Saturday that the problem with the tests appeared to be a lack of material taken from their site appeared to be a lack of material.

“The sputum samples from DCH were primarily rejected due to a lack of testable material (not enough sputum in the collection cup),” a statement from the hospital said. “Visually screening the samples at the collection site has been very difficult due to the protective measures in place so now only swabs will be done so that the provider can better directly control the adequacy of the material collected.”

DCH said in its Saturday posting that “current supply levels of swabs will only last through early next week so an extensive effort is underway to find more.” The hospital is also adding a tent for vehicles to enter to facilitate testing during rain.

The medical center said results take about five days to process.

“If your record indicates the sample was insufficient for a test and you are feeling worse, please know you can come back and get retested or see/call your doctor,” the statement says.

Tuscaloosa County had 9 confirmed cases of coronavirus as of Monday afternoon, according to the Alabama Department of Public Health. Two confirmed cases arose in Tuscaloosa before drive-in testing began on Tuesday.

Contact Montgomery Advertiser reporter Brian Lyman at 334-240-0185 or blyman@gannett.com.