Influenza Subtypes and Laboratory Diagnosed Respiratory Viruses for Winter 2017–2018, the Corporal Michael J. Crescenz Veteran Affairs Medical Center (CMCVAMC) Experience

Abstract

Introduction: Influenza occurs in outbreaks with an epidemiology that changes regularly. Although studied in the general population, there have been no studies in the English literature on the subtyping epidemiology of influenza specifically focusing on the veteran population. A quality assurance study of the influenza subtypes and respiratory viruses diagnosed in the CMCVAMC laboratory was conducted. Methods: Retrospective review of all diagnosis records from the FilmArray Respiratory Panel (Idaho Technology, Salt Lake City, UT) and the XPERT Flu/RSV XC Assay (Cepheid, Sunnyvale, CA) within the CMCVAMC laboratory was conducted from September 2, 2017, to March 3, 2018. Results: Out of 619 specimens, influenza A subtype H3 (49% of detected influenza subtypes) has predominated, though there was an increase of cases of influenza B after the week of January 27, 2018; as a result of this, the number of cases of influenza A and B cases has been roughly similar afterward. Within the veteran population at the CMCVAMC, respiratory syncytial virus (RSV) has also been commonly diagnosed by the assays, resulting in 8 cases during the week of December 2, 2017; 5 in the week of January 6, 2018; and 4 in the week of February 10, 2018. Another notable finding was detection of rarer strains like influenza A H1-pandemic, which is not reported in latest CDC data. Conclusion: RSV and influenza A (H3) have been predominant in the veteran population, though there was an increase in influenza B later in the season. In the veteran population, rare influenza subtypes (influenza A H1-pandemic) that are not currently reported as circulating in the general population were also noted. As different influenza subtypes can coinfect the same patient and even show individual responsiveness to prior vaccination or clinical presentation, the epidemiology of influenza and other respiratory viruses can have a significant clinical impact on the unique veteran population.