 Background. For more than a century a causal link between influenza and cardiovascular disease has been suspected. It is conceivable that influenza may precipitate plaque rupture, increase cytokines with central roles in plaque destabilization and trigger the coagulation cascade. Accordingly, registry studies, case control studies and a few small randomized trials, all underpowered for clinical endpoints, have demonstrated that the risk for acute myocardial infarction AMI is increased following respiratory infection and that the risk of stroke and AMI in patients with established cardiovascular disease seem to be reduced following influenza vaccination. In May 2015 a Cochrane review concluded that influenza vaccination may reduce cardiovascular mortality and cardiovascular events but bias and inconsistent results in prior studies require higher-quality evidence to confirm these findings. High costs and little commercial interest in conducting a randomized trial on influenza vaccine in cardiovascular disease stand in the way. 