This episode acts as though immunizations are brand new, untried things. The smallpox immunization was developed in 1790, almost 100 years prior to this episode! British physician Edward Jenner tested the possibility of using the cowpox vaccine as an immunization for smallpox in humans for the first time. By the 1830's, a generation had been inoculated, and there was a marked decline in smallpox cases within the United States. Most soldiers were given inoculations or vaccinations, and with all the boys having been in the army, they couldn't have not known.