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Influenza Virus Testing Methods

Purpose

Table depicting Influenza virus testing methods.

Table: Influenza Virus Testing Methods

Table 1: Influenza Virus Testing Methods
Method1 Types Detected Acceptable Specimens2 Test Time CLIA Waived3
Rapid Influenza Diagnostic Tests (antigen detection)4 A and B NP 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 NP swab, nasal swab 15-30 minutes5 Yes/No5
Immunofluorescence, Direct (DFA) or Indirect (IFA) Florescent Antibody Staining [antigen detection] A and B NP swab or wash, bronchial wash, nasal or endotracheal aspirate 1-4 hours No
RT-PCR6 (singleplex and multiplex; real-time and other RNA-based) and other molecular assays [influenza viral RNA or nucleic acid detection] A and B NP swab, throat swab, NP 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 NP swab, throat swab, NP or bronchial wash, nasal or endotracheal aspirate, sputum; (specimens placed in VTM) 1-3 days No
Viral tissue cell culture (conventional; yields live virus) A and B NP swab, throat swab, NP or bronchial wash, nasal or endotracheal aspirate, sputum (specimens placed in VTM8) 3-10 days No

Abbreviations

FDA = U.S. Food and Drug Administration
A = aspirate
B = bronchial
BAL = broncheoalveolar lavage
N = nasal
NP = nasopharyngeal
S = swab
T = throat
TR = tracheal
UTM = universal transport media
VTM = viral transport media
W = wash

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Content Source:
National Center for Immunization and Respiratory Diseases (NCIRD)
  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. Rapid molecular assays can provide results in approximately 15-30 minutes.
  6. Reverse transcription polymerase chain reaction, including FDA-approved test systems, laboratory testing using analyte specific reagents, or lab-developed reagents. Some approved molecular assays can produce results in approximately 60-80 minutes.
  • Conjunctival swabs are currently approved under FDA enforcement discretion for testing with the CDC Influenza A/H5 subtyping assay.