1. 53. In the case of quarantines, these two groups will typically overlap – some of those who will be infected under a quarantine will also be infected without a quarantine. This can only strengthened the case for quarantines. The persons who will be infected in every event and who therefore cannot be saved may be taken out of the moral calculus altogether. And doing so skews the ratio of numbers saved still further in favor of quarantines.
2. 49. These considerations, incidentally, also have implications for the management of non-communicable diseases (such as anthrax), for which the question of quarantines obviously does not arise. When such diseases are unlikely to affect many people, the aggregate costs of vaccinations (which must be administered generally) may exceed the aggregate costs of the relatively few infections that the vaccinations would prevent. But fairness may require making vaccinations available in such cases even though they are inefficient. The greatest individual costs of suffering the diseases may exceed the greatest individual costs of the vaccinations that protect against them. And although this relation between individual burdens would be reversed if the burdens were assessed ex ante, so that the costs of contracting the diseases were discounted by the unlikelihood of doing so, the arguments in the main text explain why distributive arguments may not assess individual burdens from this ex ante point of view. Some people may of course decline the vaccinations they are offered (including for the reason that their expected burdens exceed their expected benefits). Those who decline vaccinations and then become infected cannot, for reasons elaborated below, make distributive claims based on the burdens of their infections.
3. 50. Many prioritarians, for example T. M. Scanlon, do in fact accept this conclusion. See Scanlon, , supra note 46, at 229–41. A notable exception to this approach is G.E.M. Anscombe's suggestion that although “because they are more” is a perfectly intelligible reason for saving the larger group, “it doesn’t follow that a man acts badly if he doesn’t make it his reason.” Anscombe, , supra note 40, at 16–7. For Anscombe, either course in such a case – saving the smaller or the larger group – “seems O.K.” Id. at 16.
4. 17 The main text glosses over the fact that vaccinations can sometimes cause extremely severe (and even fatal) reactions in some persons, including reactions quite as severe as the symptoms of the diseases they protect against. But such reactions are extremely rare, so that they will often be much less numerous than the cases expected at the hands of the diseases if vaccinations are foregone and quarantines are employed in their stead. This will be true even with respect to fatal reactions to vaccinations against non-fatal diseases, because even diseases that are not ordinarily fatal do sometimes kill, when they beset the old or the young or when complications arise, and fatal reactions to vaccinations are generally so rare that they are outnumbered even by these exceptional cases. Fatal reactions to vaccinations therefore often should not figure prominently in the efficiency analysis of disease control. Instead, the inefficiency of vaccinations is principally caused not by the very, very few persons who suffer severe harms from being vaccinated but rather by the many, many persons who suffer much smaller harms. These small harms are so common that they come, in aggregate, to exceed the fewer but individually greater harms associated with quarantines. But fatal reactions to vaccinations might nevertheless matter to the distributive analysis upon which I am focusing here, and it might seem, therefore, that it is mistaken for me to disregard them in the main presentation of my argument. In fact, however, the few fatal reactions to vaccinations are overbalanced, even from a distributive point of view, by the many more fatalities to be expected at the hands of disease in case vaccinations are foregone. The reason for this will become plain as the distributive argument develops, and it is set out in note 52, infra.