An employee of a Rio Grande City nursing facility with dozens of positive COVID-19 cases questioned the accuracy of the results Wednesday.

The tests residents and staff received were administered by the same lab that's testing the general population in Starr County. Health officials consider those tests the "gold standard" — and stand behind the results.

Residents and staff at Rio Grande City Nursing and Rehabilitation Center in Starr County were tested last week by Emergency Diagnostic Solutions. The lab administers tests at the county's mobile testing site, said Dr. Jose Vazquez, the Starr County health authority.

"Last result that they had, it was 74," Vazquez said. That number included staff and residents of the nursing facility. Some results are still pending, according to Regency Integrated Health Services, the nursing facility's management company. 

Residents and staff were tested after an 82-year-old resident died at the facility.

He was later confirmed to have the virus. Since then, two more residents have died of the virus, according to Vazquez.

One of the employees who tested positive received the results on Saturday. That person spoke on the condition of anonymity. CHANNEL FIVE NEWS verified that the person is employed by the nursing facility.

The employee was tested on Thursday and got the results on Saturday. The test for that employee was positive. Unconvinced, the employee sought a second test from the National Guard site. The second test came back negative.

Some coworkers who also tested positive sought a second test from the National Guard site.

"The results from work were positive. And, the results from the National Guard were negative," the employee said.

Regency Integrated Health Services is also questioning the results.

"We have seen many inaccuracies with the test results and we believe re-testing is the best course of action to ensure the health and safety of our residents and staff," according to a statement provided by Brooke C. Ladner, a Regency IHS official, on Wednesday.

The doubt led to retesting of staff and residents in recent days. 

Vazquez said the tests have a high accuracy rate.

He explained the lab is using real-time reverse transcription polymerase chain reaction tests, or RT-PCR tests. These are considered the "gold standard" in COVID-19 tests, because positive results are confirmed three times before the patient receives the result. 

An RT-PCR test involves collecting a sample by using a long swab that's inserted into the patient's nose. The test works by detecting RNA strands that match those of the virus.  

"It's almost impossible to have a false positive, but it is easy to have a false negative. Because a false positive, you are talking about we are finding strands of the virus in your nasal sample when they were not there. So, that doesn't happen. So, if it's there it's there, and if it's not there, it's not there," Vazquez said.

The difference in opinion on the testing accuracy between Vazquez and Regency IHS is underscored by their relationship to each other. 

Vazquez serves as the board president of the hospital district that owns the nursing home.

In 2015, Texas created the Minimum Payment Amounts Program. It allowed nursing homes to enter into partnerships with governmental entities. Government-owned nursing facilities are able to secure more tax dollars, and the governmental entity would receive some of that money, too. 

"They [nursing facilities] would have a chance to get paid under Medicare rates rather than Medicaid raids. And, there's a very big difference in payment for Medicare beds than Medicaid beds," Vazquez said. 

Starr County Memorial Hospital has agreements with seven nursing facilities, according to state records. 

The facilities are in Rio Grande City, Harlingen, Edinburg, McAllen, Weslaco, and Raymondville. They are managed by Regency Integrated Health Services, SSC McAllen Retama Operating Company and SSC Raymondville Operating Company. Windsor Atrium is one of the nursing homes managed by Regency IHS. They've had multiple COVID-19 related deaths at the Harlingen based facility.

The hospital district also receives federal funding through those partnerships, Vazquez said. Part of those funds help with programs and expansions like the emergency center that's in progress. 

In spite of the partnership, Vazquez said the managing company retains authority over operations and decisions, like retesting.

"We overlook their operations. We make suggestions. We have an employee of Starr County Memorial Hospital that goes and makes rounds in the nursing homes on a monthly basis," Vazquez said. "So, we have oversight of the activities, but they're a private company and they have their own regulations, protocols, and staff. We do not manage anything for them," he said.

Vazquez said they're free to question the results from Emergency Diagnostic Solutions, but he believes the new tests will serve to confirm the results from the lab that does the work for the county's mobile testing site.

The latest round of tests at the nursing facility were administered June 21, according to Vazquez. They expect the results to arrive between June 26 and June 28. 

The employee who tested positive then negative went to the National Guard testing site for another test on Wednesday.

The facility told employees they cannot return to work unless they have two negative results.