Furthermore, peri- operative immunological alterations may reduce a patient s ability to respond to and to develop immunity after a vaccina- Thus, the optimal timing of perioperative influenza vaccination in patients undergoing cardiac surgery remains unclear. Whether patients should receive the influenza vaccine preoperatively or in the days or weeks after CABG should be the subject of future research. Vaccination Recommendations 1. Annual influenza vaccination should be offered to all CABG patients, unless contraindications exist (Class I; Level of Evidence B). 