Seasonal influenza vaccine effectiveness among hospitalized patients against laboratory-confirmed influenza in Lithuania

Abstract

Introduction. Annual influenza epidemics result in high morbidity and significant mortality rates worldwide. The most effective way to prevent potentially severe influenza complications is vaccination. Seasonal influenza vaccine effectiveness (SIVE) is well documented in outpatient settings, however there is a lack of data in hospitalized population. Extremely low influenza vaccination coverage of risk groups observed in Lithuania calls for more evidence of protection to help promoting vaccination among risk groups. The aim. Due to a lack of knowledge about SIVE against laboratory-confirmed influenza a study to mesure SIVE against influenza in patients admitted to hospital due to severe acute respiratory infection (SARI) in Lithuania during the 2015-2017 influenza season was performed. The co-circulation of other respiratory pathogens was also described. Materials and methods. A test-negative case-control study was conducted in four departments of two university hospitals during two influenza seasons: 2015-2016 and 2016-2017. Data on demographic and clinical characteristics were collected from patients' reports and their clinical records. [...].