Despite technological advances in public health informatics, the evaluation of infectious disease surveillance systems data remains incomplete. In this study, a thorough evaluation was performed of the West Virginia Electronic Disease Surveillance System (WVEDSS, 2007-2010) and the West Virginia Electronic Disease Surveillance System NationalEDSS -Based System (WVEDSS-NBS; March 2012 - March 2014) for Category II infectious diseases in West Virginia. The purpose was to identify key areas in the surveillance system process from disease diagnosis to disease prevention that need improvement. Grounded in the diffusion of innovation theory, a quasi-experimental, interrupted, time-series design was used to evaluate the 2 data sets. Research questions examined differences in mean reporting time, the 24-hour standard, and comparison of complete fields (DOB, gender etc.) of the data sets using independent samples t tests. The study found (a) that the mean reporting times were shorter for WVEDSS compared to WVEDSS-NBS (p < .05) for all vaccine-preventable infectious diseases (VPID) in Category II except for mumps; (b) that the 24-hour standard was not met for WVEDSS compared to WVEDSS-NBS (p < .05) for all VPID in Category II except for mumps, and (c) that most fields were complete for WVEDSS compared to WVEDSS-NBS (p < .05) for all VPID in Category II except for meningococcal disease. Healthcare professionals in the state can use the results of this research to improve the system attributes of timeliness and completeness. Implications for positive social change included improved access to public health data to better understand health disparities, which, in turn could reduce morbidity and mortality within the population.