Health officials say proper sample collection key for accurate COVID-19 self-tests

Posted at 7:48 PM, Jul 10, 2020
and last updated 2020-07-11 06:15:20-04

KANSAS CITY, Mo. — Many COVID-19 test sites across the Kansas City area are asking people to self-swab.

Three weeks ago, Aimee Pinkerton and her son Khayman Tatum got tested for COVID-19. They said they went to a drive-up test site where they swabbed themselves for the virus.

"It wasn't that bad. It kind of hurt," Tatum said.

Pinkerton performed the swab on her son and on herself but wasn't sure she did it correctly.

"I didn't feel confident," Pinkerton said."We got our negative results, which that was good."

A couple of weeks later, Tatum felt sick so Pinkerton took him for another COVID-19 test. This time, the test was performed by a nurse.

"It was probably the worst thing I've ever done," Tatum said.

Pinkerton said the test performed by the nurse went back farther into Tatum's nose.

"I watched his reaction and he was coughing and gagging," Pinkerton said.

While that test also came back negative, Pinkerton wondered if the self-test was accurate because her swab didn't go as far back.

"I do not know how anybody could do that on their own," Pinkerton said.

Ginny Boos, assistant director of infection prevention for Saint Lukes Health System, said some nose swabs are performed differently because they're different tests to begin with.

"The gold standard is the nasal pharyngeal," Boos said.

The nasal pharyngeal swab requires a sample to be collected from the back of the nose. Boos said there's also a nasal swab that gets inserted just inside the nasal cavity.

"The nasal swab doesn't go as deep but it is also reliable," Boos said.

The nasal swab also requires taking a sample from both nostrils, whereas the nasal pharyngeal swab just requires a specimen from one side.

A study from Standford showed the nasal swab, which many people may use to self-test, is accurate.

For the study, medical staff performed a nasal pharyngeal test on 30 participants, then asked the participants to self-test with the nasal swab.

While the study used a small sample size, 29 of the 30 participants got the same positive or negative results.

Boos said it's how the specimen is collected that's key to getting accurate results.

"The specimen collection process is an integral part of getting good results," Boos said. "It really just comes down to people following instructions."