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Not all coronavirus testing is equal

  • Category: Health & Wellness, Community
  • Posted On:
  • Written By: Deb Sutton, Sweetwater Memorial Public Information Officer
Not all coronavirus testing is equal

MHSC agrees nasopharyngeal swabbing is most effective method

There are a variety of tests available associated with COVID-19.

“The first step is simple. If you have questions about the novel coronavirus, talk to your provider,” said Deb Sutton, Memorial Hospital of Sweetwater County spokeswoman. “It also might help to have a better understanding of what the hospital offers and why.”

The novel coronavirus, SARS-CoV-2, typically causes an upper respiratory disease. Because of that, healthcare professionals find nasopharyngeal testing to be most effective, said Mary Fischer, MHSC Laboratory Director. For initial diagnostic testing, the Centers for Disease Control and Prevention recommend collecting and testing of an upper respiratory specimen.

“A long, thin swab is inserted deep into the nasal cavity. Some patients have asked our swabbers if we actually touched their brain,” Fischer said with a grin. “For the record, we don’t. And, the procedure only lasts a couple of seconds and it doesn’t hurt.”

MHSC agrees that the CDC recommendation of a nasopharyngeal swabbing is the most effective method for new coronavirus (SARS-CoV-2) testing, said MHSC Pathologist Dr. Cielette Karn. “Nasopharyngeal specimens offer the best opportunity to capture the virus where it resides deep in the nasal cavity,” she said.

Once a swab is taken, Sweetwater Memorial sends most specimens out to the reference laboratory for testing. Although some testing can be performed at the MHSC lab, supply constraints set by the manufacturers are the biggest reason testing is sent out.

Currently, limited in-house testing is performed on the Cepheid instrument and the BioFire. Recently, a new Cepheid analyzer with increased testing capabilities and additional BioFire modules were granted to Sweetwater Memorial by Wyoming’s State, Loan and Investment Board Coronavirus Relief Grants. This new instrumentation will give MHSC the ability to enhance turnaround time of SARS-CoV-2 testing results while still maintaining a high level of accuracy. These analyzers perform testing in under an hour, as opposed to five to seven days.

There are two kinds of tests available for COVID-19:

  • Viral tests tell you if you currently have an infection.
  • Antibody tests may be able to tell you if you have had a past infection, according to the Centers for Disease Control and Prevention. CDC does not currently recommend using antibody testing for diagnosis of acute infection. Antibody testing is not authorized by the FDA for diagnosis of COVID-19. It might not show if you have a current infection because it can take one to three weeks after an infection for your body to make antibodies. The CDC says those antibodies may be able to protect you from contracting the virus again. However, the CDC doesn’t know how much protection would be provided and how long that protection would last.

“The ability to quickly identify the SARS-CoV-2 virus while still maintaining a high level of accuracy our community deserves is the goal,” Fischer said. “We aim to use viral tests offering the greatest efficacy rate. As more tests come on the market, we will continue to evaluate them to make sure we are providing the most effective testing for our community.”

Most tests available today to detect the SARS-CoV-2 virus use polymerase chain reaction (PCR) technology, she said. It is considered a fast and inexpensive technique used to amplify or copy small segments of RNA. The entire process from amplification to detection can be completed in about an hour.

Tests used by Sweetwater Memorial:

SARS-CoV-2 by Abbott ID NOW: This test detects the virus at a molecular level and only requires a nasal swab. Because the accuracy of this test is not as reliable as other PCR methods (only about 80% sensitivity), the hospital uses this test only on symptomatic patients in the Emergency Department, the Family Medicine Clinic of Sweetwater Memorial, and Sweetwater Walk-In Clinic.

SARS-CoV-2 by Cepheid: This test uses PCR technology via nasopharyngeal swab in viral transport media. The hospital uses it for obstetrics patients, inpatients and pre-operative patients. It is highly accurate with 99% sensitivity.

BioFire Respiratory Pathogens with SARS-CoV-2 by PCR: The analyzer test is performed on a BioFire Diagnostic Machine via nasopharyngeal swab in viral transport media. The test includes 22 respiratory pathogen targets. MHSC recently added the SARS-CoV-2 test to the panel at no extra cost. Also highly accurate, this testing offers 98% to 100% sensitivity.

SARS-CoV-2 Serology (antibody): According to the U.S. Food & Drug Administration, these tests are designed to detect antibodies. “Because the antibodies are part of the body’s immune response to exposure and not the virus itself, such testing cannot be used for diagnosis of infection,” according to the FDA website. On its website – fda.gov – the FDA offers results for antibody tests that have been evaluated and a list of antibody tests it recommends healthcare providers stop using. Each test has varying degrees of effectiveness.

Other available tests, but not routinely offered at MHSC:

Saliva Collection: The FDA has yet to give general authorization for at-home collection of patient samples using saliva collection devices or other tests fully conducted at home. Anyone buying any type of at-home collection test may want to first check the FDA website.

Wyoming Health Officer Dr. Alexia Harrist believes saliva-based COVID-19 tests are a good option for surveillance testing.

“The saliva test won’t necessarily increase the turn-around time especially compared to our Wyoming Public Health Lab,” she said during a press briefing earlier this month. “It provides opportunities to do more surveillance testing … to detect cases earlier so we can implement control measures.

“At this time, the plan for saliva testing is to increase the surveillance testing that we are able to do,” she said. “It is sent off to a laboratory in another state. It’s expected to have good performance characteristics. We expect this test to perform well.”

Sweetwater Memorial continues to offer its Drive-thru COVID-19 Specimen Collection Site at the main doors of the hospital at 1200 College Drive. The swabbing station is open from 7 a.m. to 7 p.m. weekdays and from 9 a.m. to 2 p.m. weekends.

For more information on Sweetwater Memorial and its efforts to reduce COVID-19 exposure, go to sweetwatermemorial.com.