COVID-19 Updates: Specimens for SARS-CoV-2 Diagnostic Testing

The Philadelphia Department of Public Health released the following health advisory on May 12, 2020:

Summary Points:

  • COVID-19 testing is increasingly available at public health and commercial laboratories.
  • Nasal, nasal mid-turbinate and oropharyngeal swabs are acceptable specimens and should be used for sample collection when appropriate.
  • Antibody tests may indicate recent or past infection but should not be used to diagnose acute infection.

As the availability of COVID-19 testing services increases, the types of allowable specimens that can be collected for testing has also broadened. These changes are supported by the introduction of new testing platforms and emerging information about test performance using different specimens. Based upon this information, the Centers for Disease Control and Prevention (CDC) have issued guidance regarding specimens that can be submitted for SARS-CoV-2 testing. Specific laboratories have also indicated which specimens they can accept. The ability to utilize different specimens will be an important part of our ability to increase access to COVID-19 testing and potentially reduce PPE use. According to current guidance, the following specimens are acceptable and will yield comparable results:

  • Nasopharyngeal (NP) swab collected by a healthcare professional
  • Oropharyngeal (OP) swab collected by a healthcare professional
  • Nasal mid-turbinate swab collected by a healthcare professional OR self-collection supervised by a healthcare professional. Both nares should be sampled.
  • Nasal swab (anterior nares) collected by a healthcare professional OR self-collection supervised by a healthcare professional. Both nares should be sampled.
  • Nasopharyngeal wash / aspirate or nasal wash / aspirate collected by a healthcare professional

Nasopharyngeal swabs are no longer preferentially recommended. Flocked, tapered swabs should be used for nasal mid-turbinate specimens. Flocked or spun polyester swabs should be used for anterior nares specimens. Do not use swabs with preservatives or swabs with a calcium alginate tip or wood shaft.  All specimens should be placed in a sterile transport tube with any of the following:

  • Viral transport medium
  • Amies transport medium
  • Sterile saline

Please note that some point of care tests advise against placing specimens in viral transport media.  Providers should review the requirements of point of care test devices before use and confirm which specimens are accepted by their laboratory provider.  Both LabCorp and Quest who perform testing for many Philadelphia providers will accept the specimens described above.

An increasing number of facilities have also begun to offer antibody tests that do not require respiratory specimens.  It is important to note that some of these tests may lack FDA review and should not be used for the diagnosis of acute infection since antibodies may not develop until few to several days after infection.  Serologic testing, if pursued, should be reserved for persons who may have had symptoms of COVID-19 and are no longer symptomatic.  As per current CDC guidance, if an antibody test has been performed in someone with suspected COVID-19, providers should:

  • Instruct patients that a positive result indicates possible recent or prior exposure to SARS-CoV-2 or another related coronavirus.
  • Collect a specimen for a molecular test if patients are symptomatic and in a priority group for testing.

PDPH will work with public health laboratories and local healthcare facilities to help facilitate increased access to testing services.  Health providers, infection prevention practitioners, and other partner agencies should report point of care or in-house rapid tests to PDPH electronically or by phone at 215-685-6741 (after hours: 215-686-4514). When reporting, please include contact information for the case so that contact tracing can be performed (mobile phone and / or email address).

For additional information and updates about COVID-19 and diagnostic testing, please see:

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