Colorado consistently outperforms other states when it comes to health measures; Colorado’s immunization rates, sadly, are an exception.
How Does the Colorado Immunization Information System (CIIS) Benefit Colorado’s Public Health Efforts?
An Interview with Heather Roth, Deputy Immunization Branch Chief at the Colorado Department of Public Health & Environment
Immunization information systems (IIS), also 
referred to as immunization registries, are confidential, population-based, computerized databases that collect vaccination data within a geographic area. They are a confidential, secure, and centralized way for authorized users (i.e. healthcare providers, public health officials, schools) to enter immunization data, access immunization records for patients, identify missed immunizations, monitor gaps in immunization coverage important for outbreak response and targeting interventions, and to ultimately improve vaccination rates.