The threat of nosocomial transmission of seasonal flu is real and well documented. Despite decades of concerted and sustained efforts at voluntary vaccination, healthcare institutions have failed to achieve sustained high-level annual vaccination rates. By considering basic principles of biomedical ethics in which welfare concerns outweigh concerns about autonomy, and by examining the virtues of the healing professions and the derivative institutional obligations we argue that healthcare institutions have an obligation to achieve adequate vaccination rates including, if necessary, mandatory vaccination. We also discuss the practical implications of this argument for implementing such policies and touch on the potential that such policies have for future pandemic preparedness.