Many nursing homes have an influenza vaccination policy in which it is assumed that express (proxy) consent is not necessary. Tacit consent procedures are more efficient if one aims at high vaccination rates. In this paper I focus on incompetent residents and proxy consent. Tacit proxy consent for vaccination implies a deviance of standard proxy consent requirements. I analyse several arguments that may possibly support such a deviance. The primary reason to offer influenza vaccination is that vaccinated persons have a significantly reduced risk of getting the flu. This reason however cannot support the assumption that each nursing home resident is 'better off' if she is vaccinated. Neither can it support tacit proxy consent policies. More promising are arguments that take the collective nature of infectious diseases into account. A potentially strong, but ultimately insufficient, argument for non-express consent is that vaccination contributes to prevention of harm to others. Other arguments emphasize the importance of group protection: herd immunity. I discuss three collective reasons for aiming at herd immunity: solidarity, a common interest in reducing the risk of illness, and a common interest in the prevention of an influenza outbreak. The latter argument appears to be most important. An outbreak is not just detrimental to the health of residents; it is detrimental to their everyday social life as well. Outbreaks can be seen as collective evil. My analysis shows that there are valid (though not necessarily sufficient) moral arguments for a tacit proxy consent policy.