• Annual birth cohort: 77,000
• Geographic area covered: State of Arizona
• Legislation: 1998 legislation mandates providers report immunization data to ASIIS
• Percentage of immunizations given in private sector: 50 percent
• Other sources of funding: State

The dramatic growth of managed health care in most states has proven to be both an opportunity and a challenge for immunization registries. While managed care organizations (MCOs) hold large repositories of data about the shots that their enrolled children receive from participating providers, registries have needed to find ways to easily obtain that data. Conversely registries hold information that the MCOs need to demonstrate that their enrollees are up-to-date on immunizations and reach out to those children who are not up-to-date. If registries and MCOs can easily exchange information, both benefit.

Arizona has one of the country's highest managed care penetration rates and a relatively consolidated managed care market. To capitalize on this environment, ASIIS decided to develop the capacity and technical assistance for MCOs to connect to the ASIIS Authorization Gateway and use Health Level Seven (HL7), a coding standard approved by the American National Standards Institute, for exchanging immunization information.

To achieve the vision of a nationwide system of immunization registries, all immunization registries ultimately must be able to exchange information with one another (i.e., from state to state, or from a county registry to state hub registry). HL7 standards enable that exchange. While it is expected to become the principal national standard for exchanging health information, HL7 is not yet widely used among registries. The Center for Disease Control and Prevention's National Immunization Program has included the ability to exchange information using HL7 among the 13 functional requirements of a fully operational registry.

ASIIS was one of two All Kids Count projects that were able to communicate immunization information using the HL7 standard by June 2000. In 1998, the ASIIS communication gateway provided security, authentication of users, encryption and decryption of message traffic, and processing of registry requests using several different formats. Seven MCOs were able to connect to the ASIIS gateway in 1998, and an additional seven connected in 1999. Use of the HL7 format for transmitting health information was not so easily accomplished. Although ASIIS had full HL7 capability, as of June 2000 its partners were still developing their capacity. The Indian Health Service (HIS) did develop this capacity, enabling exchange of immunization data with ASIIS using HL7. ASIIS anticipated that MCOs would soon be able to exchange information with them.