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Influenza Virus Testing Methods

Table: Influenza Virus Testing Methods
Method1 Types Detected Acceptable Specimens2 Test Time CLIA Waived3
Rapid Influenza Diagnostic Tests4 (antigen detection) A and B NP5 swab, aspirate or wash, nasal swab, aspirate or wash,  throat swab <15 min. Yes/No
Rapid Molecular Assay [influenza viral RNA or nucleic acid detection] A and B NP5 swab, nasal swab <20 minutes6 Yes/No6
Immunofluorescence, Direct (DFA) or Indirect (IFA) Florescent Antibody Staining [antigen detection] A and B NP4 swab or wash, bronchial wash, nasal or endotracheal aspirate 1-4 hours No
RT-PCR7 (singleplex and multiplex; real-time and other RNA-based) and other molecular assays [influenza viral RNA or nucleic acid detection] A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum Varies (1 to 8 hours, varies by the assay) No
Rapid cell culture (shell vials; cell mixtures; yields live virus) A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum; (specimens placed in VTM8) 1-3 days No
Viral tissue cell culture (conventional; yields live virus) A and B NP5 swab, throat swab, NP5 or bronchial wash, nasal or endotracheal aspirate, sputum (specimens placed in VTM8) 3-10 days No
  1. Serologic (antibody detection) testing is not recommended for routine patient diagnosis and cannot inform clinical management. A single acute serum specimen for seasonal influenza serology is uninterpretable and should not be collected. Serological testing for detection of antibodies to seasonal influenza viruses is useful for research studies and requires collection of appropriately timed acute and convalescent serum specimens and testing of paired sera at specialized research or public health laboratories.
  2. Approved clinical specimens vary by influenza test. Consult the manufacturer’s package insert for the approved clinical specimens for each test. Ref: Leland, et al. 2007, Clin Micro Rev 20: 49-78. Approved respiratory specimens vary among FDA cleared influenza assays.
  3. Clinical Laboratory Improvement Amendments (CLIA) of 1988. http://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/index.html
  4. Chromatographic- and/or fluorescence-based lateral flow and membrane-based immunoassays. Some approved rapid influenza diagnostic assays utilize an analyzer reader device.
  5. NP = nasopharyngeal
  6. Rapid molecular assays can provide results in approximately 20 minutes. Alere i Influenza A&B was FDA-cleared for use with both nasal swabs (direct) and NP or nasal swabs in VTM, and CLIA-waived for use with nasal swabs (direct) only. Roche Cobas Influenza A/B was cleared and CLIA-waived by FDA for use with nasopharyngeal swabs only.
  7. Reverse transcription polymerase chain reaction, including FDA-approved test systems, reference laboratory testing using ASR or lab-developed reagents. Some approved molecular assays can produce results in approximately 60-80 minutes.
  8. VTM = Viral transport media

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