Comparison of Types of Influenza Diagnostic Tests
| Testing Category . | Method . | Influenza Viruses Detected . | Distinguishes Influenza A Virus Subtypes . | Time to Results . | Performance . |
|---|---|---|---|---|---|
| Rapid molecular assay | Nucleic acid amplification | Influenza A or B viral RNA | No | 15–30 min | High sensitivity; high specificity |
| Rapid influenza diagnostic test | Antigen detection | Influenza A or B virus antigens | No | 10–15 min | Low-to-moderate sensitivity (higher with analyzer devise); high specificity |
| Direct and indirect immunofluorescence assays | Antigen detection | Influenza A or B virus antigens | No | 1–4 h | Moderate sensitivity; high specificity |
| Molecular assays (including RT-PCR) | Nucleic acid amplification | Influenza A or B viral RNA | Yes, if subtype primers are used | 1–8 h | High sensitivity; high specificity |
| Multiplex molecular assays | Nucleic acid amplification | Influenza A or B viral RNA, other viral or bacterial targets (RNA or DNA) | Yes, if subtype primers are used | 1–2 h | High sensitivity; high specificity |
| Rapid cell culture (shell vial and cell mixtures) | Virus isolation | Influenza A or B virus | Yes | 1–3 d | High sensitivity; high specificity |
| Viral culture (tissue cell culture) | Virus isolation | Influenza A or B virus | Yes | 3–10 d | High sensitivity; high specificity |
| Testing Category . | Method . | Influenza Viruses Detected . | Distinguishes Influenza A Virus Subtypes . | Time to Results . | Performance . |
|---|---|---|---|---|---|
| Rapid molecular assay | Nucleic acid amplification | Influenza A or B viral RNA | No | 15–30 min | High sensitivity; high specificity |
| Rapid influenza diagnostic test | Antigen detection | Influenza A or B virus antigens | No | 10–15 min | Low-to-moderate sensitivity (higher with analyzer devise); high specificity |
| Direct and indirect immunofluorescence assays | Antigen detection | Influenza A or B virus antigens | No | 1–4 h | Moderate sensitivity; high specificity |
| Molecular assays (including RT-PCR) | Nucleic acid amplification | Influenza A or B viral RNA | Yes, if subtype primers are used | 1–8 h | High sensitivity; high specificity |
| Multiplex molecular assays | Nucleic acid amplification | Influenza A or B viral RNA, other viral or bacterial targets (RNA or DNA) | Yes, if subtype primers are used | 1–2 h | High sensitivity; high specificity |
| Rapid cell culture (shell vial and cell mixtures) | Virus isolation | Influenza A or B virus | Yes | 1–3 d | High sensitivity; high specificity |
| Viral culture (tissue cell culture) | Virus isolation | Influenza A or B virus | Yes | 3–10 d | High sensitivity; high specificity |
Negative test results may not rule out influenza. Respiratory tract specimens should be collected as close to illness onset as possible for testing. Clinicians should consult the manufacturer’s package insert for the specific test for the approved respiratory specimen(s). Specificities are generally high (>95%) for all tests compared to RT-PCR. FDA-cleared rapid influenza diagnostic tests are waived by the Clinical Laboratory Improvement Amendments of 1988; most FDA-cleared rapid influenza molecular assays are waived by the Clinical Laboratory Improvement Amendments of 1988, depending on the specimen. Adapted from Uyeki TM, Bernstein HH, Bradley JS, et al. Clinical practice guidelines by the Infectious Diseases Society of America: 2018 update on diagnosis, treatment, chemoprophylaxis, and institutional outbreak management of seasonal influenza. Clin Infect Dis. 2019;68(6):e13.