Proper collection of specimens is the most important step in the laboratory diagnosis of infectious diseases. In addition, proper temperature regulated sample storage post-collection is crucial to accurate results. A specimen that is not collected or stored correctly may lead to false negative test results.
The following information was provided by the Centers for Disease Control and Prevention (CDC) (last updated May 5, 2020).
For initial diagnostic testing for SARS-CoV-2, CDC recommends collecting and testing an upper respiratory specimen. The following are acceptable specimens:
- A nasopharyngeal (NP) specimen collected by a healthcare professional; or
- An oropharyngeal (OP) specimen collected by a healthcare professional; or
- A nasal mid-turbinate swab collected by a healthcare professional or by a supervised onsite self-collection (using a flocked tapered swab); or
- An anterior nares (nasal swab) specimen collected by a healthcare professional or by onsite or home self-collection (using a flocked or spun polyester swab); or
- Nasopharyngeal wash/aspirate or nasal wash/aspirate (NW) specimen collected by a healthcare professional.
Swabs should be placed immediately into a sterile transport tube containing 2-3mL of either viral transport medium (VTM), Amies transport medium, or sterile saline, unless using a test designed to analyze a specimen directly, (i.e., without placement in VTM), such as some point-of-care tests. If VTM is not available, see the standard operating procedure for public health labs to create viral transport medium in accordance with CDC’s protocol.
The NW specimen and the non-bacteriostatic saline used to collect the specimen should be placed immediately into a sterile transport tube.
Testing lower respiratory tract specimens is also an option. For patients who develop a productive cough, sputum should be collected and tested for SARS-CoV-2. The induction of sputum is not recommended. When under certain clinical circumstances (e.g., those receiving invasive mechanical ventilation), a lower respiratory tract aspirate or bronchoalveolar lavage sample should be collected and tested as a lower respiratory tract specimen (CDC).
COVID-19 Specimen Storage
Storage is an important component of accurate diagnostic results. CDC recommends storing specimens in a refrigerator at 2-8°C for up to 72 hours after collection. If a delay in testing or shipping is expected, clinicians should store specimens in an Ultra-low freezer at -70°C or below (CDC).
Samples may be shipped to CDC if repeated testing results remain inconclusive or if other unusual results are obtained. Please contact CDC at email@example.com prior to submitting samples.
If shipping samples to CDC: If specimens will ship without delay, store specimens at 2-8°C, and ship overnight to CDC on ice pack. If a delay in shipping will result in receipt at CDC more than 72 hours after collection, store specimens at -70°C or below and ship overnight to CDC on dry ice.
Specimens must be packaged, shipped, and transported according to the current edition of the International Air Transport Association (IATA) Dangerous Goods Regulations (CDC)
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Helmer Scientific would like to thank all frontline workers and other individuals working hard to stop the spread of COVID-19. We are here to support your sample storage needs with medical-grade refrigerators and ultra-low freezers. Contact a Helmer representative today to learn more.
“Clinical Specimens: Novel Coronavirus (2019-NCoV).” Centers for Disease Control and Prevention, Centers for Disease Control and Prevention, 14 May 2020, www.cdc.gov/coronavirus/2019-ncov/lab/guidelines-clinical-specimens.html.