2504. Influenza Surveillance and Outbreaks in the US Department of Veterans Affairs (VA): 2017–2018 Season

BACKGROUND: VA conducts yearly surveillance for seasonal influenza. VA’s large elderly population is at higher risk for influenza complications, including hospitalization and death. Herein we summarize 2017–2018 national influenza activity, outbreak and vaccination data for VA. METHODS: Hospitalizations, outpatient visits, influenza testing, and antivirals were obtained from VA data sources (October 1, 2017–March 31, 2018) and compared with prior seasons. Vaccines were captured from August 1, 2017 and vaccination percentage calculated based on VA users for each fiscal year. Outbreak data were collected from VA Issue Briefs and email survey of facility Infection Preventionists. RESULTS: Surveillance metrics for 6 seasons are presented (table). In 2017–2018, high-dose (HD) vaccine increased to 20% of total vaccine given. Outpatient visits, hospitalizations, confirmed cases and antiviral prescriptions were more than double that of previous seasons. 46 distinct outbreaks at 35 different VA hospitals were also reported this season. Among 31,611 laboratory-confirmed influenza (LCI) cases, Veterans with vaccination >14 days prior to LCI were significantly more likely to have an influenza-related hospitalization than those with no documented vaccination (782, 29% vs. 5,888, 21%, P < 0.01) and were less likely to have received HD vaccine compared with the overall VA patient population (375; 14% vs. 365,357; 20%, P < 0.01) (figure). CONCLUSION: The 2017–18 season was the most severe since VA surveillance was initiated in 2009. HD vaccine use increased over the seasons evaluated, but overall vaccination levels were stable. Nearly 90% of those with LCI had no VA-documented vaccination this season, although some may have received vaccine outside VA. Overall hospitalization rate for Veterans with LCI was high (22%). Vaccination did not reduce the likelihood of being hospitalized with influenza; however, HD vaccine may have afforded some additional protection compared with standard dose. [Image: see text] [Image: see text] DISCLOSURES: All authors: No reported disclosures.