Factors affecting influenza vaccination in adults aged 50-64 years with high-risk chronic diseases in South Korea.

Influenza is a communicable disease with most of the mortality burden falling on high-risk populations and those with pre-existing comorbidities and chronic diseases. In South Korea, adults aged 50-64 years are recommended for influenza vaccination, but no government financial support is offered to encourage vaccination uptake, which has led to suboptimal vaccination rates and significant public health concerns. The purpose of this study was to identify the factors affecting influenza vaccine uptake in adults aged 50-64 years and to compare high-risk and non-high-risk groups. We conducted randomized telephone questionnaires in South Korea on influenza vaccination-related behavioural factors in adults aged 50-64 years based on their vaccination history during the 2015-2016 flu season. The vaccination rate was 29.9% in non-high-risk adults aged 50-64 years and 41.3% in high-risk adults aged 50-64 years, which is considerably lower than the 81.7% rate in adults aged ≥65 years. Individuals who reported awareness of the potential severity of influenza, the importance and safety of vaccination, and who had experienced influenza after immunization or received a healthcare recommendation reported higher influenza vaccination rates. Therefore, highlighting awareness of influenza disease and vaccination through public campaigns and by information from healthcare professionals could represent opportunities to improve vaccination uptake in this population.