ABSTRACT
Introduction: Usability is a quality attribute that can evaluate the ease of use of user interfaces, based on standards called usability heuristics. Objective: To evaluate the usability components of the Brazilian Immunization Information System (IIS), focusing on the users and their interaction and agility with the interfaces. Materials and Methods: It was a concomitant and convergent mixed-method study that used a cross-sectional design for the quantitative approach and the indirect method of heuristic evaluation for the qualitative approach. Participants were 137 nursing professionals working in vaccination rooms, who completed a structured questionnaire on standards of usability quality, and 4 specialists in information technology, who used a semistructured form to carry out a software inspection. Descriptive and inferential statistics and the heuristic inspection were used for the analyses. Results: The evaluation resulted in 10 violated heuristics and identified 14 usability problems on the 68 screens of the IIS. The system presented simple usability problems (grade 2 severity), which can be repaired, with a low correction priority. The heuristics best evaluated were error prevention (3.03 ± 0.54) and help and documentation (3.00 ± 0.68); and the worst evaluated was visibility of system status, with a mean of 2.62 ± 0.55. Professionals with a technical education level presented a higher score on the scales for the recognition rather than recall heuristic when compared with the nurses (2.77 ± 0.49 vs. 3.67 ± 0.66, p = 0.003). Conclusion: The system provides easy access for users, however, has weaknesses in its ability to allow the users to easily achieve their goals of interaction with the interface.
