This chapter argues for a revised theory of moderate vaccine cosmopolitanism, grounded in a Thomistic natural law interpretation of the principle of solidarity, tempered by the principle of subsidiarity. Solidarity does call for love of neighbour, and therefore for global responsibilities of mutual care among nations. However, love of neighbour does not necessitate equality of treatment and resources, or equality of care and concern. Instead, it necessitates equity: love requires shared yet differentiated duties to care for those in need, according to their needs and our relationships to the most vulnerable. So, love tolerates – and even justifies – some partiality in taking care first of those in one’s own community, without abandoning outsiders to their own luck. This understanding of solidarity is predicated on the idea of equality of dignity – meaning, equal respectful consideration and loving regard among persons and nations. Equality of dignity is consistent with treating, caring, and being concerned with different people in different ways, according to their different needs and their different relationships to us, like the principle of subsidiarity suggests.