Rapid Diagnostic Testing for Influenza: Information for Health Care Professionals
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Background
Rapid influenza diagnostic tests (RIDTs) for influenza can help in the diagnosis and management of patients who present with signs and symptoms compatible with influenza. They also are useful for helping to determine whether outbreaks of respiratory disease, such as in nursing homes and other settings, might be due to influenza. See Guidance for Clinicians on the Use of Rapid Influenza Diagnostic Tests for more information.
Reliability and Interpretation of Rapid Test Results
Proper interpretation of test results is very important for accurate clinical management of patients with suspected influenza. The reliability of rapid diagnostic tests depends largely on the conditions under which they are used. Understanding some basic considerations can minimize being misled by false-negative or false-positive results.
- Sensitivities of rapid influenza diagnostic tests are approximately 50-70%, and specificities of rapid diagnostic tests for influenza are approximately 90-95%, when compared with viral culture or reverse transcription polymerase chain reaction (RT-PCR)
- False-positive results are more likely to occur when influenza prevalence in the community is low, which is generally at the beginning and end of the influenza season or periods in which influenza viruses are not circulating (e.g. summertime). View guidance on interpretation of influenza testing results when influenza viruses are not known to be circulating.
- False-negative results are more likely to occur when influenza prevalence is high in the community, which is typically at the peak of the influenza season. View guidance on interpretation of influenza testing results when influenza viruses are circulating.
Minimize False Results
- Use rapid diagnostic tests with high sensitivity and specificity.
- Collect respiratory tract specimens as early in the illness as possible, (within 3-4 days of illness onset).
- Follow manufacturer’s instructions, including handling of respiratory specimens, as described in the device package insert.
- Consider sending respiratory specimens for RT-PCR to confirm results of rapid influenza diagnostic tests especially when community influenza activity is low and the rapid diagnostic test result is positive or when the rapid diagnostic test result is negative but influenza activity in the community is high. (Contact your local or state health department for information about influenza activity).
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 |
- 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.
- 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.
- Clinical Laboratory Improvement Amendments (CLIA) of 1988. http://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/index.html
- Chromatographic- and/or fluorescence-based lateral flow and membrane-based immunoassays. Some approved rapid influenza diagnostic assays utilize an analyzer reader device.
- NP = nasopharyngeal
- 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.
- 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.
- VTM = Viral transport media
Table: Characteristics of Rapid Influenza Diagnostic Tests (Antigen Detection Only)1
| Procedure (Manufacturer/Distributor) |
Influenza Virus Types Detected |
Approved Specimens2 | CLIA Waived3 | Uses Analyzer Reader Device |
|---|---|---|---|---|
| BD Directigen™ EZ Flu A+B4 (Becton-Dickinson & Co.) |
A and B | NP5 wash/aspirate/swab Throat swab |
No | No |
| BD Veritor™ System for Rapid Detection of Flu A+B4 (CLIA-waived), (Becton Dickinson & Co.) |
A and B | NP5 swab/ nasal swab |
Yes | Yes |
| BD Veritor™ System for Rapid Detection of Flu A+B4 (Moderately Complex), (Becton Dickinson & Co.) | A and B | NP5 wash/aspirate | No | Yes |
| Binax NOW® Influenza A&B4 Test (Alere Scarborough, Inc.) |
A and B | NP5 swab, Nasal wash/aspirate/swab |
Yes | No |
| BioSign® Flu A+B4 or OraSure QuickFlu Rapid A+B Test or Polymedco Poly stat Flu A&B Test or LifeSign LLC Status Flu A&B (Princeton BioMedtech Corp.) |
A and B | NP5 swab/aspirate/wash, nasal swab | No | No |
| ClearView Exact II Influenza A&B Test or Alere Influenza A&B Test (Alere Scarborough, Inc.) |
A and B | Nasal swab | Yes | No |
| OSOM® Influenza A&B4 Test (Sekisui Diagnostics) |
A and B | Nasal swab | No | No |
| QuickVue® Influenza A/B Test6 (Quidel Corp.) |
A and B | Nasal wash/aspirate/swab | Yes | No |
| QuickVue® Influenza A+B Test4 (Quidel Corp.) |
A and B | NP5 swab Nasal wash/aspirate/swab |
Yes | No |
| RAMP Influenza A/B Assay or 3M™ Rapid Detection Flu A+B Test4 (Response Biomedical Corp.) |
A and B | NP5 swab/aspirate Nasal wash/aspirate |
No | Yes |
| SAS™ FluAlert A&B Test4 (SA Scientific, Inc.) |
A and B | Nasal wash/aspirate | No | No |
| SAS™ Influenza A Test4 (SA Scientific, Inc.) |
A only | Nasal wash/aspirate | Yes | No |
| SAS™ Influenza B Test4,6 (SA Scientific, Inc.) |
B only | Nasal wash/aspirate | Yes | No |
| Sofia® Analyzer and Influenza A+B FIA4 (CLIA-waived) (Quidel Corp.) |
A and B | NP5 swab Nasal swab |
Yes | Yes |
| Sofia® Analyzer and Influenza A+B FIA4 (Quidel Corp.) |
A and B | NP5 aspirate/ wash | No | Yes |
| TRU FLU®4 (Meridian Bioscience, Inc.) |
A and B | NP5 aspirate/swab Nasal wash/swab |
No | No |
| XPECT™ Influenza A/B4 (Remel Inc./Thermo Fisher Scientific) |
A and B | Nasal wash/swab Throat swab |
No | No |
- List may not include all test kits approved by the U.S. Food and Drug Administration. Discontinued tests not included.
- Approved respiratory specimens according to manufacturer’s package insert. Note that test performance may vary if other respiratory specimens are used.
- Ref: http://www.cms.gov/Regulations-and-Guidance/Legislation/CLIA/index.html
- Distinguishes between influenza A and B virus infections.
- NP = nasopharyngeal.
- Does not distinguish between influenza A and B virus infections when used alone.
Disclaimer: Use of trade names or commercial sources is for identification only and does not imply endorsement by the Centers for Disease Control and Prevention or the Department of Health and Human Services.
- Page last reviewed: October 25, 2016
- Page last updated: October 25, 2016
- Content source:
- Centers for Disease Control and Prevention, National Center for Immunization and Respiratory Diseases (NCIRD)
- Page maintained by: Office of the Associate Director for Communication, Digital Media Branch, Division of Public Affairs