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.
The Wisconsin Department of Health requires that specific patient data elements are reported to local public health departments within 24 hours of collection of a nucleic acid test even if the patient is asymptomatic. These data elements are included on the revised Wisconsin 2019 Novel Coronavirus (COVID-19) Patient Information Form. To meet the state requirement, clients must submit the PIF via WEDSS or by faxing to the patients local health department. Marshfield Labs no longer requires the PIF be submitted with the patient sample. NOTE: Confirmed and suspected COVID-19 disease is a Category 1 reportable condition in Wisconsin.
Marshfield Labs Wet Swab Collection Kit:
Collect either a nasopharyngeal or nasal specimen using the appropriate swab collection kit. Place swab into the Azer buffered saline 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 close the snap 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 COVID-19 test
is a high throughput nucleic acid methodology that provides results within 72
hours of specimen arrival in lab. Swab specimen submitted in saline
other than the wet swab collection kit provided by Marshfield Labs may impact
MCHS Laboratory Summary on SARS-COV-2 Assay Sensitivity and Specificity
The current SARS-COV-2 nucleic acid tests used at MCHS have been authorized for use by regulatory authorities including the FDA and CDC. These tests are highly specific (no false-positives) and are considered to be very sensitive, approaching 100%, during symptomatic disease when high titers of viral target are present, including directly before symptoms appear and following symptom resolution for several days. Analytic sensitivity of our assays was determined to be <5 copies of viral genomic RNA per microliter of sample and the assay has been validated against a panel of specimens provided by the Wisconsin State Laboratory of Hygiene (WSLH). Appropriate collection technique is a critical variable for best test performance.
Assays performed at MCHS use validated gene targets and reagents, strict quality control, and qualified testing personnel. Results generated are comparable to those produced by public health and academic laboratories nationally. 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 typical 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.
Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) (Coronavirus disease [COVID-19])