AUSTIN (KXAN) — Some doctors are raising concerns that patients may test negative for COVID-19, even when they have it.

“I have seen some tests that have come back negative, and it just seems very plausible that the patient does have or did have or is recovering from coronavirus,” said Dr. Brynna Connor, who’s been testing some patients for COVID-19 in her Austin and Lakeway offices and sending others to drive-thru testing sites.

Connor worries some of her patients may be getting false negative test results.

For the most accuracy, the CDC recommends nasopharyngeal swabs. According to the CDC, nasopharyngeal swabs, which are done by swabbing far up into the nose, are more accurate than oropharyngeal, which are throat swabs.

Connor follows the CDC’s recommendation when administering tests.

 “I have only given my patients that option in my clinic, because I believe as a clinician, I’m able to get more of the sample,” Connor said.

However, she says many other practices in central Texas are only doing throat swabs or a mixture of both.

“At least one clinic here in Austin has contacted me with concern about false negatives that can happen,” Congressman Lloyd Doggett told KXAN. “They recommend that if someone is symptomatic, has all the symptoms of coronavirus, but they test negatively, that they continue to quarantine so as to not take any risk.”

Doggett continued, saying, “Some reports indicate these tests are only 60 to 70% accurate.”

The Texas Department of State Health Services told KXAN that both nasopharyngeal swabs and oropharyngeal swabs are more than 90% reliable. However, DSHS says nasopharyngeal swabs are more sensitive to the virus.

DSHS told KXAN that although they’re preferred, some providers in Texas have had difficulty obtaining nasopharyngeal swabs, so they use oropharyngeal, which seem to be more available.

Austin Public Health says sites it is working with are using both throat and nose swabs. According to a spokesman, APH has no immediate plans to use the newly FDA approved saliva test. Austin Public Health says it will be up to medical providers whether to use that type of testing for COVID-19.