Part 12 of IVD Hall of Fame
« Rapid Influenza Detection Tests
HPV Tests »
Molecular diagnostic assays for influenza are tests based on real time polymerase chain reactions or related technologies that allow for conversion of viral RNA to DNA followed by amplification and identification of target. These assays may be performed on a variety of platforms providing identification of influenza A and B, sometimes alone or sometimes as part of a broader panel of respiratory pathogens. Some methodologies allow for viral sub-typing. The technologies used have been optimized to provide for relatively rapid testing (4 to 6 hours). Some systems have also been simplified to allow use in moderate complexity laboratories potentially increasing access to testing using molecular techniques. These tests exhibit high sensitivity (90% of more) and specificity (99%).
Before development of these assays definitive testing for influenza and sub-classification was usually performed using viral culture. This technology was available only at highly specialized labs and was more useful for tracking disease than for use in individual patient management. Molecular diagnostics allow for faster and more reliable testing which can directly aid physicians in both the decision to treat with anti-viral agents and in cases where typing or sub-typing is performed can help with selection of the best agent.
While molecular diagnostics for identification of the influenza virus are new and evolving, most practice guidelines address the use of these. CDC, for example, notes molecular testing is not needed on all patients with suspected influenza but is most appropriate for hospitalized patients if a positive test would result in a change in management. CDC also suggests molecular assays are particularly useful to identify influenza virus infection as a cause of respiratory outbreaks in institutions. Positive results from one or more ill persons can support decisions to promptly implement prevention and control measures.
There are more than a dozen FDA cleared tests. Information about the performance of these can be found on the FDA web site. Some laboratories also offer LDTs. Information on the performance of these is generally not publicly available. FDA has cleared several assays for detection of swine flu and approved at least one assay for detection of avian flu under its emergency use authorization. There is intense interest in developing improvements in molecular diagnostics like these to make them more reliable, faster, and more portable. These tests have great promise in trying to better identify and control yearly disease outbreaks and to provide physicians a tool for making optimized treatment decisions.