In Tokugawa Japan, households were organized into status groups. Every household head (typically, but not always, a man) belonged to or was at least affiliated with an occupational group that mediated his or her status and relationship with the feudal authorities. Such status groups exercised considerable autonomy—they could include and exclude members, distribute tax burdens and duties, and draft their own law codes. Status group members were also required to watch over one another, both for the sake of the group's shared interests and the stability of warrior rule. Through their parents, children were all situated within this system of group autonomy and feudal control.

But the smallpox vaccine existed independently from Tokugawa rule and its social foundations. It cared about children's bodies, not their status. Any child, whether samurai or outcaste, boy or girl, could become a link in the chain of transmission as long as the body had not yet been immunized. Vaccinations thus created impermanent networks between children that followed biological imperatives only and broke through such social constructs as territories, status identities, and family lines.

If physicians wanted to perpetuate the vaccine and rally sufficient numbers of children, they had to take advantage of the vaccine's undiscriminating nature. At the same time they also needed to work through the structures of Tokugawa society that regulated access to children's bodies. To exercise pressure on reluctant parents, vaccinators relied on domain administrators, the headmen of villages and town blocks, five-peoples' groups, and other officials and bodies of control. They also had to insist on strict compliance with the rules of their own professional networks because random transmission would have meant a lack of monitoring and quickly led to extinction of the vaccine.

As in other parts of the world where the procedure was introduced, skepticism about smallpox vaccination was rampant in late Tokugawa Japan. Unlike previous variolation techniques of Chinese origin, the administration of the cowpox vaccine required cutting the body and transmitting bodily fluids from child to child. To make matters worse, the vaccine had been derived from cows and thus crossed the boundary from animal to human, and it had been imported from foreign lands adhering to the evil creed of Christianity. These concerns were widespread, not just among uneducated people but even among some advocates of vaccination. Some physicians also opposed the new technique on grounds of Chinese medical theory or because they doubted its benefits. After all, the vaccine could be deadly if it triggered an actual outbreak of smallpox or contaminated the wound or transmitted other illnesses. Furthermore, not all vaccinations were effective, leaving some patients vulnerable to disease [Soekawa, "Gyūtō shutōhō shōrei no hanga ni tsuite," 62-63; ibid., Nihon tōbyōshi josetsu, 76-78, and 81-82; Trambaiolo, "Writing, Authority, and Practice," 221-47, 252-52; Kōzai, "Yobō sesshu to iu 'eisei'," 223-24]. To use children as "pox bases" for other children, moreover, physicians needed to cut into their arms a second time, potentially exposing them to various kinds of infections. This made it difficult to persuade parents to return for a follow-up visit.

Given such concerns, the social status of unvaccinated children was highly significant to the practice of promoting and perpetuating vaccinations. For example, the vaccination of a prince could convince the population of the benefits of the procedure [Jannetta, p. ]. Highly educated parents with knowledge of the latest scientific debates might have been easier to persuade than uneducated villagers. On the other hand, poor children or orphans were often easier to mobilize as "pox bases" for vaccine perpetuation because they lacked the power to resist and their parents tended to be more willing to accept monetary incentives [Rusnock 2009, p. 30]. This module takes up questions of social marginality on the pages The Mountain Village Effect (mountain villagers) and Vaccinating Across Status Boundaries (outcastes).