Background: A nudge intervention against Herpes Zoster, created and implemented in Italy, is presented in order to administer the Shingrix vaccine on a sample of frail patients, as required by the National Prevention Plan. Individual and contextual factors associated with vaccine adherence were investigated. Method: 300 frail adult subjects underwent a full vaccine cycle with recombinant-Shingrix vaccine (RZV vaccine). Hospital Presidia of the Salerno University Hospital Authority, a Hospital Presidium of the Salerno Local Health Authority, and the Public Health Laboratory of the University of Salerno (Campania) participated in the intervention. An ad hoc questionnaire was administered with the following scales: EQ-5D, PSS-10, MSPSS, and representations of HZ and its consequences. Results: Some variables, such as peer support, doctor–patient relationship, level of education, and perception of health, are important in vaccine adherence and information processing. The following factors emerged from the factor analysis: Trust in collective knowledge and collective responsibility (F1); beliefs about virus risk and vaccine function (F2); information about virus and symptomatology (F3); and vaccine distrust (F4). Factor 4 correlates negatively with social support indices (R = −0.363; p < 0.001). There is a significant relationship between factor 3 and satisfaction with national information campaigns (F = 3.376; gdl = 5; p-value = 0.006). Conclusions: Future vaccination campaigns should be built with the aim of personalizing information and developing contextualized strategies, starting from understanding the stakeholders involved, cultural contexts, and organizational settings.