It seems that health is not a common good, because health characterizes an individual. In scholastic terms, it is a qualitative accident of a living substance, an organism. Thus:
An individual’s life and health are particular goods, not common goods. It is an obvious metaphysical truth that my health and my life can only be mine and are not shared in common with anyone, and certainly not with the political community at large. At its heart, “public health” is an oxymoron since “the public,” as an abstraction, has no health to speak of. Only individuals are healthy or not.
By contrast, a common good, “by definition, must extend to all members of the political community (that’s what “common” means).”
Of course, “common” is a word used in many ways. “Health” or “healthy” are Aristotle and Aquinas’s go-to examples of analogous terms. The dog is healthy, he is eating healthy food, his bark is healthy, etc.
A difficulty often encountered in understanding the common good arises from the analogous meaning of “common.” The common good is not common in the way that a name is common to many individuals, for instance, in the way that “human” can be truly said of Socrates, Plato, and Theaetetus. This is a universal term—what is universal in praedicando. Rather, the common good is common as a universal cause, what is universal in causando. For instance, the mind of an artist is a universal cause of his distinctive style in his various works.
The final cause of a group of people, the goal that shapes their association’s desires (whether that goal arises from human nature or human choices), is a common good. It is a single cause whose effects are manifold and derive their order from the cause as such. For instance, within the domain of a pick-up basketball game, victory is the common good of each team. As the victory of “shirts” or “skins” (but not both), it is a (small) universal cause, a common good. Each team is commonly seeking victory—the name belongs to both—but they are not seeking a common victory. Finally, the mark of the common good is present here, since the good of victory is not diminished by being shared (unlike the share of individual points scored by each player on the team).
Thus, on the one hand, health is not a common good, even though it can be a property common to many individuals. Health is a private good, since your health cannot be my health, unlike the case where my victory is also your victory since we were on the same winning team. In light of this, we can see that it is an error to conceive of the essence of the common good as simply the private benefit of individuals due to a common source. This is especially true of material goods that are distributed from a common stock or available in common and sometimes denominated “common goods” (bona communia; for instance, public roads or public utilities).
However, on the other hand, common goods of human communities are paradigmatically types of order aimed at as goods, where the good of such an order arises through the common aims, choices, and desires of the individuals. For example, the medievals conceived of the political common good as justice and peace. Now, these terms both have uses that signify private goods (the virtue of justice in this person’s soul, his spiritual or mental peace, etc.). This shows the need for the distinctiveness of the good of order.
For instance, in the case of a well-trained basketball team, they possess a good of order that arises from the various relationships enabled by their training and practice, which have disposed each member of the team towards the others as teammates. They play well together. Their victory is a common good—an extrinsic common good—but their being a “well-oiled machine”, and so both aiming at and maintaining that order, is also a common good—an intrinsic common good. Each player as such is perfected as a part of the team in a way different from his simply being skilled as an individual player, and his being a teammate does not diminish the share in the good of order of the others.
Similarly, justice—the rectitude of moral and legal order among citizens in their various natural and voluntary communities (families, neighborhoods, parishes, etc.)—and peace—the tranquil life of such a flourishing, ordered community—are integral components of the political common good precisely as a good of order. The order among members of the community is rooted in them as parts, but only exists among them as a whole. The members all aim at the achievement and maintenance of that order. So, to promote the continuance and flourishing of the parts of political community—the “little platoons”, families, associations, parishes, etc.—is to promote a common good, for it is to promote a good of order shared in without diminishment.
Public health, the good of order of parts of political community arising out of individual health, which good can be estimated by parameters like herd immunity, while not the highest of goods, is a condition of further goods of order. However, it is a condition that is a good of order because it emerges out of the relationships between members of the community and their health in an individual sense. As such a good of order that can be aimed at and shared in, without thereby being lessened, it is a common good.