Posters as a Tool to Improve Hand Hygiene among Health Science Students: Case—Control Study

(1) Background: Numerous educational interventions have been conducted to improve hand hygiene (HH) compliance and effectiveness among nursing students, with mixed results. The aim is to evaluate the effectiveness of posters as a teaching tool and factors associated with HH quality. (2) Methods: A pre-post experimental intervention study was conducted with a total of 293 nursing students randomly assigned to two groups (experimental and control) who, before and after HH, took cell culture samples from their non-dominant hands. Only the experimental group was exposed to the poster. (3) Results: In the experimental group, significant differences were observed among students older than 22 years (p = 0.017; V = 0.188), with a higher percentage of failures (15.7% vs. 3.6%). Poster displaying was associated with passing, other variables being equal, although without statistical significance (ORa = 2.07; 95% CI = 0.81–5.26). Pre-practice hand contamination was weakly associated with lower HH quality (ORa = 0.99, 95% CI = 0.99–0.99). (4) Conclusions: The use of posters as a teaching method shows indications of efficacy. Prior hand contamination slightly affects the quality of HH. Further evaluation of teaching methods is needed to ensure good technical performance of HH to prevent the spread of infectious diseases during the COVID-19 pandemic.