Prevalence of Seasonal Influenza Vaccination in Chronic Obstructive Pulmonary Disease (COPD) Patients in the Balearic Islands (Spain) and Its Effect on COPD Exacerbations: A Population-Based Retrospective Cohort Study. - Ruiz Azcona L; Roman-Rodriguez M; Llort Bove M; van Boven JF; Santibáñez Margüello M (International journal of environmental research and public health, 2020)