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Susceptibility testing to Paxlovid and remdesivir

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Requisition Forms

Reference Details


Susceptibility testing to Paxlovid and remdesivir for SARS-CoV-2 by focus reduction assay and/or sequencing.

Test Category:
Susceptibility Testing
Illnesses and Diseases:
  • Respiratory tract infections
  • COVID-19

Original specimen or viral isolate, minimum volume 1.0 mL required, if no additional testing requested.

Collection Method:

Original Specimens: Nasopharyngeal swab specimens, throat swab specimens.  Viral Isolates: N/A

Specimen Processing, Storage and Shipping:

Keep samples refrigerated or frozen at -80 °C until shipped for testing.  Avoid repeated freeze thaw cycles.  Ship on dry ice.

Transportation of Dangerous Goods:

Shipping of specimens shall be done by a TDG certified individual in accordance with TDG regulations. For additional information regarding classification of specimens for the purposes of shipping, consult either Part 2 Appendix 3 of the TDG Regulations or section 3.6.2 of the IATA Dangerous Goods Regulations as applicable.

Patient Criteria:

Suspected or confirmed SARS-CoV-2 infection.

Accompanying Documentation:

Completed requisition form (Requisition for antiviral susceptibility of SARS-CoV-2).  Sender lab name, address, and telephone number must be included for samples to be processed.  Also include laboratory identifier, patient date of birth, patient gender, type of specimen, and date collected.  If possible, please include patient travel history, extent of SARS-CoV-2 activity, and date of collection relative to antiviral use.



Methods and Interpretation of Results:

Susceptibility to antivirals (Paxlovid and remdesivir) is determined by both a laboratory developed focus reduction assay, as well as sequence analysis.  The focus reduction assay assess the ability of the viral isolates to replicate in the presence of antiviral drugs.   Whole genome sequencing will be used to compare the sequence data with known wild-type sequences and screen for the presence of any mutations known to cause resistance to the antiviral.

Turnaround Time:

30 calendar days

Phone #: (204) 789-6047
Fax: (204) 789-2082