Respiratory syncytial virus burden among adults during flu season: an underestimated pathology

Information on the role of respiratory syncytial virus (RSV) in adult patients with influenza-like syndrome is scarce.

To assess the clinical characteristics of RSV in adult patients with respiratory manifestations during a regular influenza season.

Prospective study in a tertiary Spanish hospital from December 2015 to February 2016. The study population included only adult patients with either community-acquired or hospital/healthcare-associated influenza-like illness, according to the European Centre for Disease Prevention and Control criteria. Samples were analysed using a rapid molecular assay (Xpert^® Flu/RSV). RSV-positive patients were compared with a randomly negative control group and with an influenza-positive control group.

Twelve hundred patients with influenza-like respiratory infection were included. Overall, 114 of the samples (9%) were positive for influenza and 95 (8%) were positive for RSV. When RSV-positive and influenza-positive patients were compared, RSV-positive patients were older (57.7 vs 48.9 years; P = 0.03), and their disease was more frequently healthcare-related (26/95, 27.3% vs 5/114, 1.7%; P < 0.001). They also had significantly more antibiotics prescribed (77/95, 81.0% vs 70/114, 61.4%; P < 0.001) and more frequently needed hospital admission (93/95, 97.8% vs 69/114, 60.5%; P < 0.001). Mortality was also significantly higher in RSV-positive patients (14/95, 14.7% vs 7/114, 6.1%; P = 0.04).

RSV is a major cause of moderate-to-severe respiratory infection during the influenza season; acquisition is frequently nosocomial or healthcare-related; and mortality is significantly higher than with influenza virus infection. The use of a rapid molecular test as a first-step diagnostic technique is necessary to ensure that isolation measures are implemented and that spread is prevented.