Influenza virus antigen
Last updated: Wednesday, 17, March, 2004
| Item | Process |
|---|---|
| Specimen | Nasal swab, nasal wash or aspirate, throat swab for IF. Dry swabs, that is not in transport medium, are required for rapid immunoassays and should be tested within 1 hour of collection. Dry swabs should also be collected for PCR testing. |
| Method | Nucleic acid detection by immunoassay, IF, nucleic acid detection after amplification (PCR). |
| Application | Nucleic acid detection by immunoassay allows point of care testing for rapid diagnosis of acute influenza due to influenza virus types A and B, and thus can be used to guide the use of antiviral treatment. IF and PCR testing are more sensitive. |
| Interpretation | A positive result confirms infection with influenza types A and B. Rapid immunoassays generally do not distinguish between types A and B, whereas IF testing may. Rapid immunoassays have a sensitivity of ~80%, so a negative result does not rule out the diagnosis. False positives are uncommon. |
| Reference | Cox NJ and Subbarao K. Lancet 1999; 354: 1277-1282. |