The Centers for Disease Control and Prevention (CDC) recommends influenza testing for all patients with a suspected diagnosis entering a hospital. Clinical influenza diagnoses do not require a flu test, but influenza tests can assist with clinical decisions related to infection prevention and control, antiviral treatment and diagnostic testing. Clinicians should consider factors such as cost, speed and accuracy when choosing an influenza testing method for their practices.
What Factors Contribute to the Best Flu Test?
What constitutes the “best” flu test for your practice will depend on your priorities. The sensitivity of frequently used Food and Drug Administration (FDA)-approved diagnostic tests range from approximately 80-95%, but costs or testing time tend to rise with those rates. To account for these factors, we will categorize the best tests by the cheapest, fastest and most accurate.
Cheapest Flu Tests
Rapid influenza diagnostic tests (RIDTs) have one of the lowest costs among FDA-approved influenza tests on the market. According to Nature, RIDTs cost around $15 per test — compared to rapid molecular tests, they tend to have higher false negative rates, too.
Fastest Flu Tests
Clinical guidelines from the Infectious Diseases Society of America (IDSA) state that the time to results for influenza testing ranges from 15 minutes to 10 days, depending on the method used. Two influenza testing methods provide results in less than an hour:
• RIDT: RIDTs offer results within 15 to 30 minutes, making them faster than most FDA-approved flu tests. With an analyzer reader device, these tests can reach a sensitivity of 80% or higher while delivering rapid results. Due to their lower sensitivity rates than other methods, the CDC recommends confirming RIDT results with a molecular assay.
• Rapid molecular assay: Rapid molecular assay tests detect influenza with high specificity at a sensitivity between 90-95%. In exchange for their high speed and accuracy, practices must pay more than RIDTs per rapid molecular assay test and invest in a testing platform. Compared to an RIDT’s average cost of $15, a molecular assay test can cost up to $45.
Most Accurate Flu Tests
Culture and molecular assay testing offer the highest sensitivity and accuracy rates out of common influenza tests. Compared to RIDTs, they have a slower time to results or higher costs. These testing methods include:
• Rapid molecular assay: Compared to RIDTs, rapid molecular assays have higher sensitivity and a lower false negative rate. A 2017 meta-analysis found that in people with influenza, RIDTs had a false negative rate of 45%, while molecular assays had a rate of just 8%. The 90-95% sensitivity rate enables it to detect influenza at lower viral loads than RIDTs. However, this high level of sensitivity can lead to a higher contamination risk than RIDTs.
• Standard and multiplex molecular assays: The IDSA recommends using standard and multiplex molecular assays in hospitalized patients over RIDTs because of their high accuracy rate. When a rapid molecular assay test isn’t available, these tests can confirm negative RIDT results and provide results within one to eight hours.
• Rapid cell or viral culture: The CDC and IDSA recommend rapid cell and viral culture tests for antigenic and genetic characterization instead of diagnosis because they can take up to 10 days to deliver results. When necessary, they can also confirm a negative result from an RIDT or immunofluorescence assay.
Purchase Your Flu Tests From Mercedes Scientific
Mercedes Scientific sells influenza testing kits and supplies from brands such as Silaris, Veritor and OSOM. For more information about our point-of-care and rapid testing products, contact our team online.