The availability and use of commercial influenza rapid diagnostic tests by laboratories and clinics have substantially increased in recent years.
· Influenza rapid diagnostic tests are screening tests for influenza virus infection.
· They can provide results within 15 minutes.
· More than 10 rapidflu test kits have been approved by the U.S. Food and Drug Administration (FDA).
· Rapid tests differ in some important respects:
· Some can identify influenza A and B viruses and distinguish between them.
· Some can identify influenza A and B viruses but cannot distinguish between them.
· Some tests are waived from requirements under the Clinical Laboratory Improvement Amendments of 1988 (CLIA).
· Most tests can be used with a variety of specimen types (see Influenza Diagnostic Table), but the accuracy of the tests can vary based on the type of specimen collected (for example throat swab versus nasal swab).
· FDA approval is based upon specific specimen types.
· The rapid tests vary in terms of sensitivity and specificity when compared with viral culture or RT-PCR. Product insert information and research publications indicate that:
· Sensitivities are approximately 50-70 percent
· Specificities are approximately 90-95 percent
· Specimens to be used with rapid tests generally should be collected as close as is possible to the start of symptoms and usually no more than four to five days later in adults. In very young children, influenza viruses can be shed for longer periods; therefore, in some instances, testing for a few days after this period may still be useful.
Content adapted from the CDC.