Effect of vaccination, comorbidities and age on mortality and severe disease associated with influenza during the season 2016–2017 in a Spanish tertiary hospital oleh Enrique Gutiérrez-González, José M. Cantero-Escribano, Lidia Redondo-Bravo, Isabel San Juan-Sanz, Ana Robustillo-Rodela, Emilio Cendejas-Bueno, Influenza Working Group