Age-Stratified Epidemiology of Respiratory Pathogens and the Value of Customizable Syndromic Testing Using the LIAISON PLEX Respiratory Flex Assay

Molecular syndromic assays have advanced respiratory diagnostics by enabling the simultaneous detection of multiple pathogens from a single sample. However, fixed-panel designs may not align with age-specific prevalence patterns or evolving epidemiological trends, limiting clinical utility and reimbursement viability. In this study, 1,520 positive nasopharyngeal swabs from symptomatic individuals collected during the 2022-2023 respiratory season were analyzed using the LIAISON PLEX Respiratory Flex Assay to evaluate the benefits of customizable, tiered testing strategies. Diagnostic yields from a standard-of-care (SOC) panel were compared with tiered (core-plus-reflex) frameworks across pediatric (<21 years), adult (22-64 years), and elderly (>65 years) cohorts. Weighted analyses revealed that 99.8% of cases were viral, while bacterial pathogens accounted for fewer than 1%. The most commonly detected viruses included SARS-CoV-2 (28.2%), HEV/HRV (17.1%), Influenza A (11.9%), and HCoV (7.4%). Age-related differences were observed, with HEV/HRV and AdV more common in pediatric patients, whereas SARS-CoV-2 and Influenza A predominated in adults and the elderly. SOC panels captured only 58% of infections overall and 33% in pediatric patients, whereas the tiered testing approach identified ≥99% of infections using flexible core-plus-reflex panels. Moreover, core panel targets alone accounted for over 76% of all detections. These findings underscore the diagnostic, clinical, operational, and cost-management value of age-informed, customizable testing frameworks to improve detection, reduce unnecessary testing, and support stewardship.