2518. The Role of Non-Influenza Viruses in the Seasonal Viral Respiratory Illness: A Epidemiologic Study From October 2016–March 2017

BACKGROUND: Influenza virus (IV) is a leading cause of morbidity and mortality worldwide; however, understanding the contribution of non-influenza viruses (NIV) to the annual burden of respiratory illnesses (RI) is evolving. Improvements in diagnostic techniques, including the increasing clinical use of respiratory viral PCR panels (vPCR), have markedly advanced our understanding of the contributions of NIV to the “influenza season.” METHODS: A retrospective analysis of all vPCR results from one hospital system, collected between October 1, 2016 and March 7, 2017, including inpatient and outpatient samples was performed. 2,047 vPCR tests were reviewed; after removing those with undetermined results and internal control samples, 1,924 were analyzed. Data points abstracted included detection and identification of virus, and date of detection. We compared the total and monthly rates of NIV with IV, throughout the study period. RESULTS: Of 1,924 vPCR results, 985 (51%) were positive for a respiratory virus. Of these, 302 (31%) were IV, and 683 (69%) were NIV. For every month studied, the ratio of NIV to IV exceeded 50%, including the height of the season. The most commonly detected viruses were Influenza A (30%), Rhino/Enterovirus (24%), RSV (19%), Coronavirus OC43 (7%) and Metapneumovirus (5%). The peak influenza incidence temporally coincided with the national peak months of January and February. The NIV incidence paralleled the trend in IV incidence, dominated by Rhino/Enterovirus and RSV, but without a specific virus driving the trend. CONCLUSION: Non-influenza respiratory viruses cause substantial viral RI during the winter months. Many viral syndromes during the height of influenza season have traditionally been attributed to IV, including influenza-like-illness (ILI); however, these can now be better characterized using patient-specific vPCR panels, leading to improved understanding of NIV epidemiology. Even during the period of highest IV incidence, NIV infections were more common than IV. Understanding the high prevalence of NIV infections may improve the judicious use of both antibiotics and antivirals. There may also be a role for refinement of ILI, including best practices for diagnosis and treatment. DISCLOSURES: All Authors: No reported disclosures.