721. Clinical Respiratory Syndromes and Association with Influenza Clinical Diagnostic Testing and Antiviral Treatment among Children Hospitalized with Acute Respiratory Illness, 2015–2016

Background We investigated clinical influenza testing and treatment in children hospitalized with acute respiratory illness (ARI) who had distinct respiratory syndromes. Methods Children <18 years old with ARI were enrolled at seven hospitals in the New Vaccine Surveillance Network (NVSN) between November 1, 2015–June 30, 2016. ICD10 admission diagnosis codes were grouped to define syndromes of bronchiolitis, asthma, pneumonia, and croup. At clinician discretion, influenza testing with a rapid influenza diagnostic test or molecular assay was performed on respiratory samples. As part of the study, each site performed influenza testing using molecular assays on mid-turbinate nasal and throat swabs from all enrolled children. Analysis was restricted to influenza season; children who received antivirals before hospitalization were excluded. Results Among 2,134 children with available ICD10 codes, on preliminary analysis 1,119 (52%) had influenza testing ordered by a clinician: 111 (10%) were positive, and 57 (51%) of 111 received antiviral treatment. Of the 2,134, 858 (40%) had one of the four mutually exclusive syndromes (table). Hospital clinical testing per clinician discretion was influenza positive in 16 of the 858 children (percent positivity per syndrome ranged from <1% to 38%; table). Research study testing of children not undergoing clinical influenza testing identified 11 additional positives. Antiviral treatment was highest for pneumonia patients. Conclusion Understanding testing and treatment practices by clinical syndrome may help to identify missed opportunities for influenza diagnosis and treatment. Table: Bronchiolitis Asthma Pneumonia Croup n = 392 n = 320 n = 117 n = 29 n % n % n % n % Age <5 years 391 >99 156 49 76 65 23 79 <2 days from illness onset to admission 87 22 171 54 28 24 15 52 >1 known underlying condition 84 21 277 87 62 53 6 21 Hospital clinical testing performed 209 53 90 28 68 58 8 28 Positive influenza 1 <1 4 4 8 12 3 38 Antiviral treatment 0 1 6 0 Research study result in children without hospital clinical testing Additional positive influenza 1 3 5 2 Antiviral treatment 0 0 3 0 Disclosures J. Englund, Gilead: Consultant and Investigator, Consulting fee and Research support. Novavax: Investigator, Research support. GlaxoSmithKline: Investigator, Research support. Alios: Investigator, Research support. MedImmune: Investigator, Research support. N. B. Halasa, sanofi pasteur: Investigator, Research support. GSK: Consultant, Consulting fee. Moderna: Consultant, Consulting fee.