New point of care test is highly specific but less sensitive for influenza virus A and B in children and adults

The importance of rapid diagnosis of influenza has increased with the availability of neuraminidase inhibitors, which need to be commenced within 48 hr of symptom onset. Furthermore, the recent development of influenza-like clinical syndromes with novel aetiologies (severe acute respiratory syndrome, SARS) has increased the need for rapid and accurate near-patient diagnosis. A new, modified point of care (POC) diagnostic test (ZstatFlu) was assessed on 469 nasopharyngeal aspirates (NPAs) and 260 nose/throat swabs (TS) taken from children and adults. The test was specific (77-98%) for all specimen types for influenza virus A and B, depending upon incubation conditions. However, it was less sensitive, detecting 65-77% of specimens confirmed as positive on culture, direct immunofluorescence or PCR testing. A positive test is useful, for both directing initiation of therapy in the clinician's office, and making a positive diagnosis of influenza in patients with influenza-like clinical syndromes.