Immunization Information Systems

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Immunization Information System (IIS) also (Immunization Registries) is a confidential, computerized information system that collects and consolidate vaccination information from multiple healthcare providers and helps in clinical decision support by generating reminder and recall notifications and asses the vaccination coverage within a defined demographic area.


In United States, each state maintains immunization repositories separately. Statistics has shown that by two years of age, over 20% of the children in the U.S. typically have seen more than one healthcare provider, resulting in scattered paper medical records.


Immunization information systems (IIS) help providers and as well as families by consolidating immunization information of children as well as adults into one reliable source which save money by ensuring that children get only the vaccines they need and improve office efficiency by reducing the time needed to gather and review immunization records. So immunization registries system plays a key role in shaping health care reform.

IIS also helps providers and parents determine when the immunization are due and ensures that children get only the vaccinations they need. These systems are capable of exchanging immunization information with the immunization healthcare providers using health standards to work more efficiently.

IIS has huge benefits over its cost and some of the examples are:

  • can help physicians in reducing over-vaccination for new patients, sending out reminders and recall for patients immunization
  • save signification amount of staff time spend on calling other providers for vaccines and immunization
  • easily interoperable with other systems
  • Automates vaccine inventory and expediting order and tracking them

It also records adult immunization history provided by public, private clinics, health care providers and other local agencies. IIS support the immunization program by targeting population at high risk for vaccine preventable diseases. It also consolidate immunization records from different sources and provide a single source of information center for parents, school, day care etc. IIS also protects the privacy and confidentiality of all users.


IIS interface has been designed such that it can share data efficiently and unambiguously with other healthcare systems including EHR. Without following a standard message format for communication the IIS programmer will take an incredible amount of design time to convert data coming from different system into a non-standard format understood by the IIS. IIS has adopted the national standard electronic message protocol HL7 to overcome such and many other overhead. IIS are guided by government issued standards to protect privacy of all its users including families, providers. Each IIS must maintain a written policy that clearly defines notifications and choices provided to parents, IIS usage, and disclosure information. HIPPA privacy policy control the use and discloser of protected health by entities called covered entities like health provider, health plan and health care clearing house. But most of the registries do not perform such coverage function so they are not required to comply with HIPPA. The key finding is that IIS can securely and confidentially receives immunization data from healthcare provider. Also it allows access to authorize users only so that only desired author can get access to their children immunization record.

Information standardization

Immunization registries don’t exist by themselves. It needs to be connected and exchanging immunization data electronically with other health and clinical information systems including EHR. Healthcare providers, private and public practice clinic supporting EHR in their environment can transmit patient’s immunization record to IIS electronically. EHR support such functionality within the system.

IIS support national health standard interface message format, HL7 so that can:

  • easily communicate with EHR based public and private clinics, hospitals
  • save cost that would have done through help sending paper record, multiple phone calls
  • and also supports in generating immunization reports to Centers for Disease Control and Prevention (CDC)

The greatest informatics triumphs of this are the interoperability and security capabilities of these systems because most of the EHR supports HIPPA’s transaction policy for safe and secure data transfer to other information system.


They have been evaluated and there have been numerous studies and research time spend onto evaluate its performance and services. The cost behind supporting electronic transfers of child and adult immunization record to the IIS is not significant and the benefits are huge. A case study based on usage of IIS data for quality measurement done by Priority Healthcare; Michigan based health organization, to investigate the use of IIS data on quality measurement, Healthcare Effectiveness Data and Information Set (HEDIS) compliance. In this study was conducted from 2004 to 2007 by collecting data and are simulated in the Priority’s health information system database in absence of IIS data. And these simulated data are then compared with the IIS database and the results are very significant. For 2007, IIS data increased observed immunization rates from 6.49 to 54.13 percentage points for childhood immunizations and 57.63 to 77.97 percentage points for adolescent immunizations. The most significant source of savings was in administration of the health plan's Physician Incentive Program, which saw 18,881 fewer chart reviews from 2004 to 2007 when IIS data were used compared with when they were not used. Total costs of using IIS data were estimated to be $14,318 and net benefits were $107,854 – which corresponding to a benefit-to-cost ratio of 8.06.


  1. Immunization Registries, HL7, and HIPAA
  2. Laura A Zimmerman, Diana L Bartlett, Kyle S Enger, Kimiko Gosney,and Warren G Williams. Influenza vaccination coverage: findings from immunization information systems. Published online 2007 July 27. doi: 10.1186/1471-2431-7-28.
  3. Centers for Disease Control and Prevention (CDC). Progress in Immunization Information Systems - United States, 2008. MMWR Morb Mortal Wkly Rep 59, no. 5 (2010): 133-5.
  4. O'Connor AC, Layton CM, Osbeck TJ, Hoyle TM, Rasulnia B. Health plan use of immunization information systems for quality measurement. Am J Manag Care. 2010 Mar;16(3):217-24.

Submitted by Purabi Panigrahy