Severe Illnesses Associated With Outbreaks of Respiratory Syncytial Virus and Influenza in Adults

Abstract Background Recent reports have described the contribution of adult respiratory syncytial virus (RSV) infections to the use of advanced healthcare resources and death. Methods Data regarding patients aged ≥18 years admitted to any of Maryland’s 50 acute-care hospitals were evaluated over 12 consecutive years (2001–2013). We examined RSV and influenza (flu) surveillance data from the US National Respiratory and Enteric Virus Surveillance System and the Centers for Disease Control and Prevention and used this information to define RSV and flu outbreak periods in the Maryland area. Outbreak periods consisted of consecutive individual weeks during which at least 10% of RSV and/or flu diagnostic tests were positive. We examined relationships of RSV and flu outbreaks to occurrence of 4 advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) due to medically attended acute respiratory illness (MAARI). Results Occurrences of all 4 MAARI-related hospital advanced medical outcomes were consistently greater for all adult ages during RSV, flu, and combined RSV–flu outbreak periods compared to nonoutbreak periods and tended to be greatest in adults aged ≥65 years during combined RSV–flu outbreak periods. Rate ratios for all 4 MAARI-related advanced medical outcomes ranged from 1.04 to 1.38 during the RSV, flu, or combined RSV–flu outbreaks compared to the nonoutbreak periods, with all 95% lower confidence limits >1. Conclusions Both RSV and flu outbreaks were associated with surges in MAARI-related advanced medical outcomes (hospitalization, intensive care unit admission, intubated mechanical ventilation, and death) for adults of all ages. Data from hospitalized adults in Maryland over 12 consecutive years revealed surges in hospitalization, intensive care unit admission, mechanical ventilation, and death related to medically attended acute respiratory illnesses during outbreaks of respiratory syncytial virus and influenza.