PHII’s Charisse LaVell and Treonda Chapman summarize the history of immunization information systems (IIS) in the U.S., how IIS changed during COVID-19 and what’s ahead.

You may or may not have ever heard the term “immunization information systems” (IIS), but you’ve almost certainly interacted with one, whether you’ve needed to validate your child’s vaccine records to enroll them in school, or you received a COVID-19 vaccination in the early months after the initial roll-out.

IIS are core to the public health infrastructure in the United States. The push for the development of IIS across the country grew out of a nationwide measles outbreak in the early 1990s. During the measles outbreak, the lack of easily obtainable data about individual children’s vaccination statuses led to a swifter spread of the epidemic, and in many tragic cases, death. Several key partners, including the federal government, the Robert Wood Johnson Foundation and even the Public Health Informatics Institute (then operating under the name All Kids Count), joined together to support states, territories and other large public health jurisdictions in launching their own IIS. This effort–often termed the “let a thousand flowers bloom” era of IIS–saw each public health authority making its own complex decisions on how to best build its own separate IIS. (You can learn more about this history here.)

In the decades since, IIS have grown and matured into one of the most comprehensive and longest standing sets of public health information systems in the country today. 

This slideshow requires JavaScript.

IIS after COVID

Historically, IIS partners used these systems in scrappy and resource-low conditions, but public health faced new, unprecedented challenges during the pandemic; they were suddenly having to scale up to handle massive amounts of data tracking COVID vaccines for children and–in some jurisdictions–adults. Each jurisdiction took a different approach, all finding a way to rapidly pivot to brace for these changing public health needs, from collaboration among separate IIS in the same regions to standing up vaccine credentialing systems.

As COVID increased the demand not just for IIS data, but for new and increased uses of that data, IIS staff and partners were finding that COVID was greatly highlighting a particular, long-standing issue in IIS. Though the “let a thousand flowers bloom” approach had been crucial to the early and rapid creation of IIS in the 1990s by removing the need for a national accord to a standardized approach to IIS, it now also meant highly siloed individual IIS. The lack of interoperability meant that rapid or simple data exchange between different jurisdictional IIS simply wasn’t possible. This was a difficulty even in normal times, but under the tidal wave of COVID data, the lack of interoperability across healthcare providers, programs and jurisdictions was a more glaring challenge than ever.

All the same, the pandemic was a testament to the essential nature of IIS. Without IIS reporting and tracking during COVID, national vaccination efforts would have been cut off at the knees. The reporting and surveillance capabilities of IIS empowered public health to obtain accurate, timely and complete reporting during critical stages of the pandemic, which in turn contributed to the national vaccination campaign that ultimately slowed the rate and severity of ongoing COVID outbreaks.

What’s next for IIS?

As we look ahead to the future, IIS still face several long-term challenges, particularly around scaling up and training its workforce and continuing on with sufficient and sustainable funding to operate well. The public health workforce experienced a mass exodus in the difficult–and at times traumatic–midst of the pandemic. Reinforcing the strength of the public health workforce by hiring and training new public health professionals continues to be difficult.

In recognition of the challenges that IIS face, PHII makes available a suite of free, CDC-funded resources on our IIS Learning Hub to IIS staff and their partners. These resources include eLearning courses, job descriptions for core IIS roles, data modernization guidance for IIS, and toolkits with step-by-step guidance for doing some of the essential work of IIS.

About the Authors

Senior Informatics Analyst Charisse LaVell, MPH, and Informatics Analyst Treonda Chapman, MPH, provide guidance to PHII’s IIS efforts.