26195 COVID 19 Nucleic Acid Test (NAT) PCR

​COVID 19 PCR, SARS-CoV-2, Coronavirus

This is a qualitative nucleic acid test for the detection of nucleic acid in nasopharyngeal swabs from patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Patients may have mild to severe respiratory illness with symptoms of sore throat, cough, fever and shortness of breath and many have had complications including pneumonia.  Patients may also be asymptomatic individuals with recent known or suspected exposure to SARS-CoV-2 or asymptomatic individuals without known or suspected exposure to SARS-CoV-2 for early identification in special settings. 

NOTE: Confirmed and suspected COVID-19 disease is a Category 1 reportable condition in Wisconsin.

Marshfield Labs Wet Swab Collection Kit:

Collect a nasopharyngeal specimen using the appropriate swab collection kit. Place swab into the transport tube and carefully break off the swab shaft against the side of the tube at the score line. Discard the top portion of the swab shaft. Securely tighten the cap of tube.

Transport specimen at 2-8°C to Marshfield Labs as soon as possible.  If specimen cannot be tested within 72 hours of collection, it should be frozen at -70°C or colder until tested

​Nasopharyngeal or Nasal Swab

The Aptima® SARS-CoV-2 assay is a nucleic acid amplification in vitro diagnostic test intended for the qualitative detection of RNA from SARS-CoV-2 isolated and purified from upper respiratory specimens.

MCHS Laboratory Summary on Aptima® SARS-COV-2 Assay

The performance characteristics of the Aptima SARS-CoV-2 assay for nasal collected specimen, were determined by the manufacturer, and granted an Emergency Use Authorization (EUA) by the FDA for this specimen type.

Appropriate collection technique is a critical variable for best test performance.

Negative results do not preclude SARS-CoV-2 infection and should not be used as the sole basis for patient management decisions.  Negative results must be combined with clinical observations, patient history, and epidemiological information.

Detection of Genetic Variants of SARS-COV-2

Several variant strains of SARS-COV-2 have recently emerged. Test manufacturers, CDC and the WSLH are constantly evaluating assay ability to detect variant strains and regularly share updates with clinical laboratories nationwide. Currently, all recognized variant strains are being detected by our testing methods.  The reported test results will not, however, differentiate between the ancestral pandemic strain and that of a SARS-COV-2 variant strain.  Further genetic characterization by whole genome sequencing is required to identify which variant is present.

Marshfield Labs Partnership with WSLH on Surveillance for Genetic Variants of SARS-COV-2

Wisconsin Department of Public Health, WSLH and partner laboratories are conducting active surveillance for novel and variant SARS-COV-2 strains using whole genome sequencing. Marshfield Labs is supporting this surveillance effort by selecting positive specimens from geographically dispersed Wisconsin locations, hospitalized patients, vaccine break-through cases, and re-infected patients for surveillance sequencing.  Marshfield Clinic Research Institute will perform the sequencing surveillance and report their results to the Wisconsin Department of Health Services (WDHS).

Note that sequencing results will not be reported to the Provider or the patient. Sequencing is performed strictly for public health surveillance purposes and is not meant to advise patient care. 

​Positive - SARS-CoV-2 nucleic acid detected.

Negative - No SARS-CoV-2 nucleic acid detected.

Indeterminate - Result is indeterminate due to PCR inhibitor present in the specimen.  Consider repeat specimen if clinically indicated.

Inconclusive - Result of testing is inconclusive.  Laboratory performed repeat testing, but failed to provide a negative or positive result that may be due to interfering substances, lack of sufficient viral target because sample is either too early in the infection process or after most of it has been cleared, collection-associated problems, or other limitations. The result cannot be called positive or negative.

Consider submitting a repeat specimen if clinically indicated.