Utah paused this type of COVID-19 test. But was it defective or left out in the cold?

Utah health officials stopped using the GenBody brand of rapid antigen tests this week after an analysis found that nearly two-thirds of the testing results came back with results different from the final PCR tests — most producing false-negative results.

But the company behind the test is now speaking up in support of their product, as the state health department begins a review of what went wrong.

In the statement to KSL.com, GenBody wrote it reaffirms its "commitment to the production of accurate, cost-effective COVID-19 rapid antigen tests" amid the Utah health department's decision to pause the use of the tests. The statement goes on to say the company is working with Utah health officials to figure out the cause behind the results.

It's something that the South Korean company, with a California-based distributor, says has not appeared elsewhere among the "millions (of tests) administered in nearly every state."

Does that mean the tests in Utah weren't handled or administered according to instructions? That's one possibility being investigated.

GenBody says that "due diligence" on their end has yet to lead them to believe there's a problem with the test. They add that the test has been "validated in multiple, independently run clinical trials," including one recently conducted at Emory University.

David Yoo, the CEO and founder of GenBody America, added that the company hasn't completed its investigation and will continue work with Utah health officials "to review the procedures used to administer the tests."

"The results from Utah were surprising, but we are working tirelessly and diligently with the help of the Utah Department of Health to understand what may have contributed to these discordant results," he said.

Many of the testing sites the Utah Department of Health sponsors began using GenBody tests late last year, as a new surge in COVID-19 cases emerged in the state. It wasn't until early last week that there were any signs of problems with the brand, state health officials said.

The state said one of the testing sites reported that there was a discrepancy between the site's GenBody rapid results and PCR tests from an individual tested through both methods in the same visit. This sparked a review of about 18,000 same-day PCR and GenBody tests, which found only 38% of rapid tests matched PCR results. Among Utahns displaying obvious signs of COVID-19 symptoms, only 41% tested positive. Those numbers prompted the sudden pause, which was announced on Sunday.

The review of the GenBody tests, according to Utah Department of Health officials, will seek to determine whether they were ineffective due to a design flaw or whether it was the result of a shipping malfunction or operator error on the end of state-sponsored testing sites.

Based on what the health department has said about the issue, a Utah testing expert — independent to either side — told KSL-TV on Tuesday that he suspects shipping or storage issues may be behind the faulty results. Jeff Midgley, the owner of the Utah company Lab to You, has spent 30 years in the health care industry and says all rapid tests are fragile, which is why it's important that users follow the instructions outlined by testing manufacturers.

In GenBody's case, there is a strict temperature at which the tests must be kept. The company received an Emergency Use Authorization from the U.S. government last summer, which is when its COVID-19 tests entered the marketplace.

The Food and Drug Administration has since posted the company's 19-page instruction manual online. It states all kits should be stored between 35.6 and 86 degrees Fahrenheit, and all "test devices, reagents, specimens and/or controls" should be at about room temperature before the time of testing. This is, according to the document, anywhere between 15 and 30 degrees Celsius — about 59 to 86 degrees Fahrenheit.

There are other instructions, such as the foil pouch holding supplies shouldn't be opened until the time of testing, all devices should be placed on a level surface, and all specimens should be tested immediately.

"If improper procedures were used, that would invalidate all test results," Yoo explained. "We are unequivocally committed to ensuring that every precaution is taken so that people who rely on these tests can be confident in the accuracy of the results."

Midgley explains this is a common issue with tests. In some cases, the solution may look cloudy if it's compromised by temperature. Many of the tests that Lab To You receives come with a thermometer that will turn gold once the container has been exposed to extreme temperatures.

If they see gold, they know to throw away the tests because it's compromised.

"If they're stored in cold environments (or) super hot environments, it can make the test go bad," he said. "That doesn't necessarily mean they were bad tests but could have it been shipped wrong? Could it have been stored wrong? ... All those will create false positive or negative results, and that's what we're seeing here in Utah right now."

There are no set guidelines for how tests are handled at Utah's testing sites, a spokesperson for the state health department told KSL.com. All testing sites are instructed to get testing guidelines "directly by the test manufacturer," instead. When asked if the health department conducts inspections of testing sites, the health department official added that it does not have that sort of authority, aside from reviewing procedures at its own sites.

It's unclear if the testing sites in Utah that received differing results followed the guidelines outlined by GenBody. At the same time, it's possible that the differences in rapid antigen testing and PCR testing led to some of the differences the health department saw.

Antigen rapid testing doesn't always produce the same results as PCR tests because antigen tests are meant to capture cases where someone has a high viral load more than trying to capture if they are infected, public health experts told NPR last month. PCR tests can even produce positive COVID-19 results for weeks, meaning someone could test negative for COVID-19 through an antigen test and test positive in a PCR test based on the differences of the tests.

All of these are possibilities for the issues the state health department reported, and they will all likely be reviewed over the next few weeks in addition to the tests themselves.

Between the Utah pause of GenBody tests and the FDA's recent recall of SD Biosensor rapid tests over "reports that the test kits were illegally imported into the U.S.," Midgley says he's aware that people might have concerns with rapid antigen testing.

However, he said people should still have confidence in rapid antigen testing and their results as long as they follow the instructions for each type of test properly.

"It doesn't mean all rapid testing is over and done because they are still out there and still great tests," he said. "(Keep them at) room temperatures. Don't leave them in your car — heat or cold will ruin those tests."