 The investigators propose to perform a single center, double-blind, randomized, placebo-controlled crossover trial analyzing the beneficial effect of the influenza vaccine in patients undergoing cardiac surgery. This study assesses the impact of the influenza vaccination on the overall systemic inflammatory response and investigates the functional and clinical outcome in vaccinated patients after cardiac surgery. The study sample will consist of patients undergoing cardiac surgery at Health Sciences North randomized into 2 groups: 1 those who receive the vaccine or placebo preoperatively, or: 2 those who receive the vaccine or placebo 4-6 weeks postoperatively. Subjects in both groups will be compared using standard laboratory tools to assess the level of various pro- and anti-inflammatory cytokines IL-6, IL-8,TNF-alpha, IL-10 as well as other cardiac and inflammatory markers troponins, CRP, at different time intervals intra- and post-operatively. Other clinical outcomes will also be collected prospectively and compared between the 2 groups. These include hemodynamic parameters as well as major postoperative events. Further assessments will include the Frailty Index and Scale in patients 65 and length of stay after surgery 