What is the testing procedure for coronavirus disease 2019 (COVID-19)?

Updated: Jun 16, 2020
  • Author: Medscape Drugs & Diseases; more...
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Answer

Answer

Conduct all testing for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in consultation with a healthcare provider. [4, 5] Specimens should be collected as soon as possible once a decision has been made to pursue coronavirus disease 2019 (COVID-19) testing, regardless of the time of symptom onset.

Specimen types

Upper respiratory specimens

For initial diagnostic testing for SARS-CoV-2, collecting and testing an upper respiratory specimen is recommended. Acceptable specimens include the following [4] :

  • A nasopharyngeal (NP) or oropharyngeal (OP) specimen collected by a healthcare provider; or

  • A nasal midturbinate (NMT) swab collected by a healthcare provider or by a supervised onsite self-collection (using a flocked tapered swab); or

  • An anterior nares (nasal swab) (NS) specimen collected by a healthcare provider or by onsite or home self-collection (using a flocked or spun polyester swab); or

  • NP wash/aspirate or nasal wash/aspirate (NW/NA) specimen collected by a healthcare provider

Immediately place swabs into a sterile transport tube containing 2-3 mL of either viral transport medium (VTM), Amies transport medium, or sterile saline, unless using a test designed to analyze a specimen directly (ie, without placement in VTM), such as some point-of-care tests. [4]  If VTM is not available, see the standard operating procedure for public health labs to create viral transport medium in accordance with Centers for Disease Control and Prevention's (CDC’s) protocol.

Immediately place the NW specimen and nonbacteriostatic saline use to collect the specimen into a sterile transport tube. [4]

Lower respiratory specimens

Another option is to test lower respiratory tract specimens. [4]  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 it is clinically indicated (eg, 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. [4]

Safely collecting and handling specimens

Maintain proper infection control when collecting specimens. [4]  See Biosafety FAQs for handling and processing specimens from suspected case patients.

  • When collecting specimens or when within 6 feet of those suspected to be infected with SARS-CoV-2, maintain proper infection control, and use recommended personal protective equipment (PPE), which includes an N95 or higher-level respirator (or a facemask if a respirator is not available), eye protection, gloves, and a gown.

  • For providers who are handling specimens but are not directly involved in specimen collection (eg, self-collection) and not working within 6 feet of the patient, follow standard precautions; gloves are recommended. While in the healthcare facility, at all times, healthcare personnel are recommended to wear a form of source control (facemask or cloth face covering).

Properly handling bulk-packaged sterile swabs for upper respiratory sample collection

Sterile swabs for upper respiratory specimen collection may be packaged in one of two ways [4] :

  • Individually wrapped (preferred when possible)

  • Bulk packaged

Bulk-packaged swabs may be used for sample collection; however, exercise care to avoid SARS-CoV-2 contamination of any of the swabs in the bulk-packaged container. [4]

  • Before engaging with patients and while wearing a clean set of protective gloves, distribute individual swabs from the bulk container into individual disposable plastic bags.

  • If bulk-packaged swabs cannot be individually packaged, use only fresh, clean gloves to retrieve a single new swab from the bulk container; close the bulk swab container after each swab is removed, and leave it closed when not in use to avoid inadvertent contamination; store opened packages in a closed, airtight container to minimize contamination; keep all used swabs away from the bulk swab container to avoid contamination.

  • For all swabs, only grasp the swab by the distal end of the handle, using gloved hands only.

  • When patients are self-collecting their swabs under clinical supervision, hand a swab to the patient only while wearing a clean set of protective gloves; the patient can then self-swab and place the swab in transport media or sterile transport device and seal; if the patient needs assistance, help the patient place the swab into transport media or a transport device and seal it.

Discussion

Clinicians should work with local and state health departments to coordinate testing for individuals with possible COVID-19 through public health laboratories, or work with commercial or clinical laboratories using viral tests granted an Emergency Use Authorization (EUA) by the US Food and Drug Administration (FDA). [3, 4, 5]

Clinicians should use their judgment to determine if a patient has signs and symptoms compatible with COVID-19 and whether the patient should be tested. [3]  Most patients with confirmed COVID-19 have developed fever and/or symptoms of acute respiratory illness (eg, cough), but some infected patients may also present with other symptoms.

Clinicians are encouraged to test for other causes of respiratory illness (eg, influenza) in addition to testing for SARS-CoV-2, depending on patient age, season, or clinical setting; detection of one respiratory pathogen (eg, influenza) does not exclude the potential for coinfection with SARS-CoV-2. [3]  These tests should not delay testing for SARS-CoV-2.

Symptoms and presentations may be different in the pediatric population; therefore, consider referencing the Centers for Disease Control and Prevention (CDC) guidelines for COVID in neonates and for multisystem inflammatory syndrome in children (MIS-C). [3]

Other considerations that may guide testing are epidemiologic factors such as the occurrence of local community transmission of COVID-19 infections in a jurisdiction. [3]  

Healthcare providers should report positive results for SARS-CoV-2 to their local/state health department. [3, 4, 5]  Clinical laboratories should NOT attempt viral isolation from specimens collected from people suspected to have COVID-19 unless this is performed in a biosafety level 3 (BSL-3) laboratory. Test for other pathogens as part of the initial evaluation, but this should not delay testing for SARS-CoV-2.


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