Protection Motivation Theory (PMT) holds that individuals under threat base their protection decisions on threat and coping appraisals. In the case of preventable communicable diseases, the theory holds that motivation for vaccination will be higher the more alarming a person’s threat appraisals and the more promising her coping appraisals are. This study aims at describing how the influence model of PMT accommodates different changes and conditions: the addition of new factors such as knowledge, health literacy, and attitudes, and the inclusion of several highly similar threats in the form of different communicable diseases. The question raised is: Do people, when making vaccination decisions, think of vaccination as a unified entity or as separate units? In the first case, they would show similar factors across different vaccinations, probably thinking of the common biomedical functioning of vaccination. In the latter case, the predictors would change from vaccination to vaccination, and people might have different treatments of the subject in public communication on their minds. Data came from a representative survey among adult Swiss residents. Among the results are the following: PMT is affirmed; people show a unified way of determining their motivation to vaccinate; knowledge contributes strongly to protection motivation; and neither public discussion of threats nor experiences among acquaintances shows much of an impact.