Table 1.

Comparison of available influenza diagnostic tests.¹⁰ Serologic testing on paired acute- (within 1 week of illness onset) and convalescent-phase (collected 2–3 weeks later) sera is limited to epidemiological and research studies, is not routinely available through clinical laboratories, and should not inform clinical decisions. *The amount of time needed from specimen collection until results are available. ^†Compared with rRT–PCR tests; rRT–PCR tests are compared with other testing modalities including other rRT–PCR assays. ^‡RIDTs include tests that are CLIA waived (can be performed in an outpatient setting) and tests that are moderately complex (can be performed only in a laboratory). Clinical specimens approved for RIDTs vary by test, and may not include all respiratory specimens. ^¶Performance of these assays relies heavily on laboratory expertise and requires a fluorescent microscope. ^§Requires additional testing on the viral isolate. ^|The performance of rRT–PCR assays specific for 2009 H1N1 influenza has not been established for bronchoalveolar lavage and tracheal aspirates. If testing these specimens for 2009 H1N1 influenza, consider testing in parallel with a nasopharyngeal, nasal, or oropharyngeal swabs or a nasal aspirate. ^#See discussion above on available rRT–PCR assays

Influenza diagnostic tests	Method	Availability	Typical processing time*	Sensitivity† for H1N1 2009 influenza (%)	Distinguishes H1N1 2009 influenza from other influenza A viruses?
RIDT‡	Antigen detection	Wide	0.5 h	10–70	No
Direct and indirect immunofluorescence assays (DFA and IFA)¶	Antigen detection	Wide	2–4 h	47–93	No
Viral isolation in tissue cell culture	Virus isolation	Limited	2–10 days	—	Yes§
Nucleic acid amplification tests (including rRT–PCR)|	RNA detection	Limited#	48–96 h (6–8 h to perform test)	86–100	Yes