Children's Bodies and the Transfer from Kyoto to Fukui
As a back-up for the glass containers, Kasahara Ryōsaku recruited parents with young children for arm-to-arm transfers, two children from Kyoto and three from Fukui.
On 11/16 (according to the lunisolar calendar used in Tokugawa Japan), Kasahara initiated the transfer from Kyoto to Fukui by vaccinating the two children from Kyoto. After confirming that pustules had developed on their arms, he traveled with the children and their parents to an inn in Nagahama on Lake Biwa, an important way station en route to Fukui. On 11/22 the children's pustules had ripened, and Kasahara extracted lymph from their arms and transferred it to the three children from Fukui, who had traveled to Kyoto for this purpose together with their parents. The children from Kyoto then returned home, and Kasahara and the remaining families hiked back to Fukui, braving a blizzard and extremely deep snow as they crossed Tochinoki Pass (Kasahara Hakuō-hitsu senkyōroku). On 11/24, the party reached the highway station of Imajō, where physicians from Fuchū were already waiting with three local children in tow. Kasahara vaccinated one of these children as a back-up. On 11/25, the travelers arrived in the castle town of Fukui, where Kasahara immediately began to vaccinate further children. He probably used the lymph from the glass container at that time, as the pustules of the arriving children would not yet have been ready for extraction (Fukui-ken Ishikai 1968, 177).
Although arm-to-arm transfer turned out to be unnecessary in the case of this relatively short journey, it later became the preferred method of transmission due to its reliability. The author of “Gyūtō Kaihei” (Uncovering cowpox) from 1852 argued that scabs in particular should only be used in rare cases, for example for long-distance transfers, because they were more likely to result in spurious pocks and did not offer the same degree of protection as direct transmissions (Umihara 2014, 196).