As early as September, $5, rapid-result antigen tests, purchased by the U.S. government, could start arriving in Memphis, offering 15-minute turnaround times expected to appeal to employers and schools.

The Trump administration purchased 150 million of Abbott Lab’s BinaxNOW COVID-19 Ag Card tests for $760 million, according to U.S. Department of Health and Human Services.

Germantown education leaders formalize stance on state testing amid pandemic

“By strategically distributing 150 million of these tests to where they’re needed most, we can track the virus like never before and protect millions of Americans at risk in especially vulnerable situations,” HHS Secretary Alex Azar said in a statement.

Tennessee could receive up to 1 million of the test kits, according to a release Friday from U.S. Sen. Lamar Alexander.

“This could mean as many as one million additional tests just during October for use in Tennessee hospitals, doctors’ offices and other healthcare settings to help schools, colleges, child care centers and workplaces continue to safely reopen,” he said.

Antigen tests so far have not been widely used in Shelby County in part because they are not as sensitive as the molecular nasal or saliva tests.

Doctors scratch heads over CDC guidance for less testing

“It has to do with how good the test is in terms of sensitivity and specificity, and that is based on the prevalence of disease,” said Dr. Manoj Jain, the infectious disease expert who is advising Memphis Mayor Jim Strickland in the pandemic.

“If you have low prevalence of a disease and you have a test that doesn’t have very good sensitivity and specificity, then you get a lot of false positives and false negatives.”

For that reason, antigen tests are best used in people with symptoms or in front-line screening where possible cases can be followed up with more precise testing, he said.

But a test that is easy to give and produces rapid results has a large role to play, Jain said, because it helps people get used to the idea of frequent testing.

“This test will make it easier at doctors’ offices for people who are symptomatic. It will change the culture of testing, making it more acceptable by a larger population, which is without a doubt, one of the core solutions for us to get back to a safer and more normal way of living,” Jain said.

While the standard polymerase chain reaction (PCR) tests show the presence of the virus itself, antigen tests detect proteins on the virus.

Cases among student-athletes will be investigated like others, health officials say

“It is the same technology we use for pregnancy tests,” said Dr. Scott Strome, executive director of the College of Medicine at University of Tennessee Health Science Center. “It’s cool technology, but it is old technology.”

The advantage is that the test does not require a laboratory for processing, which makes it good for use in pre-operation patients in hospitals.

“You can have truly point-of-care of testing without having to clean the machine and put in the next sample,” Strome said.

Abbott received emergency-use authorization from the U.S. Food & Drug Administration for BinaxNOW on Wednesday, Aug. 26.

It will offer a phone app so people can show their test results to organizations that require proof of negative status to enter.

“But, remember, no one is confident, or at least I am not confident, that a negative test result means that you are negative,” Strome said. “In the majority of cases, that will be true, but there are significant concerns that with a negative test result you could still be positive.”

The company plans to ship tens of millions of the tests in September and ramp up to 50 million tests a month in early October.

In data submitted to the FDA from a clinical study conducted by Abbott with several U.S. research universities, the BinaxNOW test demonstrated sensitivity of 97.1% (positive percent agreement) and specificity of 98.5% (negative percent agreement) in patients suspected of COVID-19 by their health care provider within seven days of when symptoms appeared.

Although the test is given with a nasal swab, it is not the deep, pharyngeal swab, Jain said, that most people who have been tested in Memphis have received.

University of Memphis workers knock safety efforts on campus

It also differs from the antibody test, which is a blood test to determine whether a person has antibodies or immunity to the coronavirus.

Shelby County has capacity to test more than 9,000 people a day now and soon is expected to be able to conduct 10,000 tests at day.

For the last two weeks, testing centers here have been operating at 70% or less capacity.

As of Thursday, the transmission rate — the average number of people one person infects — had inched up from 0.89 to 0.95. On Aug. 6, it was 0.82.

The number of cases in the county is now doubling every 47 days. On Aug. 17, cases were doubling every 40 days.