Table. Characteristics of influenza test types used for US domestic influenza virologic surveillance*.
| Characteristic | RIDTs† | Virus isolation | Direct fluorescent antibody tests | Molecular tests‡ | Antiviral resistance functional tests | Antigenic tests§ | Genetic sequencing |
|---|---|---|---|---|---|---|---|
| Result type |
Influenza positive or negative AND
type A or B (for most tests) |
Virus growth |
Influenza positive
(type A or B), negative, or inconclusive |
Influenza type and/or subtype
positive, negative, or inconclusive |
Resistant or not to adamantanes and neuraminidase inhibitors |
Antigenic relatedness of viruses to vaccine or reference viruses |
Genetic structure
and relationship to previously circulating influenza viruses |
| Time to results |
<30 min;
most differentiate positive influenza A and B |
Traditional:
3–10 d
Rapid:
1–3 d |
1–4 h |
15 min–6 h |
≈1 d |
5–8 h |
3–5 d
(excluding isolation) |
| CLIA¶ category | Varies: CLIA-waived to moderate complexity | High complexity | Varies: moderate to high complexity | Varies: CLIA-waived to high complexity | High complexity | High complexity | High complexity |
*CLIA, Clinical Laboratory Improvement Amendment; RIDT, rapid influenza diagnostic tests. †http://www.cdc.gov/flu/professionals/diagnosis/rapidlab.htm#table2. ‡http://www.cdc.gov/flu/pdf/professionals/diagnosis/molecular-assay-table-1.pdf. §Hemagglutination inhibition, microneutralization, and focus-reduction assays (https://www.cdc.gov/flu/professionals/laboratory/antigenic.htm). ¶ CLIA categories for laboratory complexity (https://wwwn.cdc.gov/clia/Resources/TestComplexities.aspx).