Early detection of influenza A and B infection in infants and children using conventional and fluorescence-based rapid testing.

BACKGROUND: The appropriate management of infants and children with influenza depends on the accurate and timely diagnosis, ideally at the point of care (POC).
OBJECTIVES: To evaluate the use of simultaneous RSV/influenza rapid testing with QuickVue™ test strips as well as (the use of) novel, fluorescence-based, rapid influenza antigen testing (SOFIA™) in infants and children with influenza-like illness (ILI). STUDY
DESIGN: The Study was conducted in a real-time surveillance program at the Charité Department of Pediatrics in collaboration with the National Reference Centre for Influenza at the Robert Koch Institute (RKI) in Berlin, Germany (Charité Influenza-Like Disease=ChILD Cohort).
RESULTS: During the 2010/2011 influenza season, 395 infants and children were simultaneously tested using QuickVue™ FluA&B and RSV10 rapid tests at POC compared to independent RT-PCR. Sensitivities were 62.7/67.8% for Influenza/RSV overall, but highest in infants <1 year with 76.0/76.2%. The evaluation of the fluorescence-based rapid test SOFIA™ with frozen laboratory samples (derived from the 2008/2009 and 2010/2011 national surveillance) yielded sensitivities of 97.7/86.7/86.7/81.7% for influenza A(H1N1)pdm09/A(H3N2)/B-Victoria/B-Yamagata in samples with CT values <34, and 80.2/79.8/67.5/62.5% for all CT values combined. The same method used at POC with 649 consecutive ChILD patients in 2011-2012 yielded sensitivity/specificity/PPV/NPV values of 78.9/99.7/96.6/97.3%. Again, sensitivities were highest in infants (85.7%) and small children <2 years (88%).
CONCLUSIONS: Fluorescence-based rapid antigen testing provides a highly sensitive and specific tool for POC diagnostics of acute influenza in the paediatric age group, especially in infants and small children <2 years, when viral loads are at their peak and treatment decisions are imminent.