1142: Why Immunization Information Systems Matter

JOHN SHEEHAN: 

This is Public Health Review Morning Edition for Tuesday, June 9, 2026. I'm John Sheehan with news from the Association of State and Territorial Health Officials.

Today: Immunization Information Systems, or IISs. They quietly power much of the nation's vaccination infrastructure and help clinicians track patient immunizations, support outbreak response, and guide decision-making. ASTHO senior director of state health policy, Andy Baker-White, tells us why IISs are essential to modern public health, how opt-in versus opt-out policies affect vaccine data completeness, and what lawmakers, providers, and the public should understand as policy debates continue.

ANDY BAKER-WHITE: 

Yeah, so Immunization Information Systems, or a lot of times we shorten it to IISs, are registries that are supported by different jurisdictions, both state and local. You know, I think one thing to keep in mind is that these are confidential computerized databases that record all of the immunization doses that are administered by providers to patients who are living in those states and cities, and so forth. It's really a backbone for public health, because it generates information that can be used to support not just clinical decisions between a patient and their provider, but also for public health action when it comes to communicable and infectious disease. Vaccines that are administered by these providers are documented, become the data within the ISS, and they can be used to determine when immunizations might be needed. This information can be used to help remind patients of upcoming vaccinations, and as for public health, you know, can really be used to guide public health responses to outbreaks, help agencies see where additional vaccine coverage might be needed, or you know what areas might be impacted by an outbreak. So, they're really, you know, can be there to not just help the individual in protecting themselves by remembering, "Oh yeah, I'm due for this next vaccine," but also for the communities at large in helping to stop the spread of disease,

SHEEHAN: 

And you mentioned in a recent Health Policy Update how these systems can really differ across states and different municipalities. How do those variations in systems affect the overall data usefulness or completeness to the big picture?

BAKER-WHITE: 

Yeah, the different laws and policies that we talked about in the article reflect some of the policies around ISS that do impact completeness. So, one is the level of consent that is needed in order for people to participate in the IIS, whether that is implicit consent, meaning that an individual is automatically participating, whereas they may have the option to opt out, or whether the system is set up as an opt-in or explicit consent process. So, if it's an opt-in system, then the completeness is probably not going to be as robust as a system that's opt-out, where everyone is required to at least start, and they might be able to opt-out, but you're going to capture, you know, more people than if it's an opt-in. So, the more people that you have in the system, the more data, the better picture that you're going to have of the community's vaccine status, you know what the potential impact of an outbreak, of a disease outbreak may be on the community, because you have a better idea of who has the vaccines, and so forth.

SHEEHAN: 

Sure, and you know, you can imagine reasons for different agencies having different, you know, models, whether it's opt-in, opt-out, mandatory. But from a public health, big picture perspective, what are the trade-offs when you sort of give those options of, you know, having to say, "Yes, I want that?"

BAKER-WHITE: 

Yeah, like the opt-in systems, you know, you have less completeness. And so, I think this is just, this could again, like, just impact the readiness, the response, you know, of a public health action. You know, kind of determining, you know, is more vaccine for this disease needed? Do we need to purchase that? And thinking back, you know, also like, just to the clinical decision-making piece of it, the part between the provider and the individual patient. You know, it's not going to be something that the provider would be able to perhaps access, and know that, oh, I should talk to this patient about, you know, the vaccine that they need. So, there can also just be that personal, individual costs as well.

SHEEHAN: 

And you pointed out the benefit to automatic enrollment, where you're signed up, and that really can be critical for outbreak response.

BAKER-WHITE: 

Yeah, yeah. It's good to think back to how the ISS came in to be, which, you know, they really, the idea really goes back to a measles outbreak that occurred in the late '80s, early '90s, where several children died. A lot, you know, 1,000s of children were infected. You know, doctors, you know, they just didn't have the view on, you know, the vaccines that their patients had received, and whether their patients were protected. So, you know, the importance of allowing our physicians, our doctors to know the vaccination status of our children, of adults, again the ability to provide reminders for any sort of needed updates, and again the impact that this data, this information can have in responding to an outbreak.

SHEEHAN: 

Yeah, and on the other side, from there, sort of the patient side of the opt-in, opt-out data sharing. And then there's the provider side. What providers have their own reporting requirements and data access policies? How can those mandates and policies affect clinicians' ability to make these decisions?

BAKER-WHITE: 

Yeah, so, there is some variation among the states, among the jurisdictions, especially when it comes to whether providers are required to report child immunizations or adult immunizations. So, more states require child immunizations to be reported by providers than adult immunizations. So, for adult populations, especially in states that don't require providers to report on adult vaccines, there can be a missed opportunity there by their providers to remind them to advise them about vaccines that you know, even as adults, we need to have routine vaccines. Also, you know, with the reporting by providers, it's important, you know, that we have policies that are bi-directional. So, it's not just the provider reporting to the system that they've given a vaccination to someone, but also that the provider can access that data of that patient. People change their doctors, they move, so being able to have that information also cross state lines is important.

SHEEHAN: 

Yeah, and you know, obviously from the greater public health perspective, you know, having that data and having that access again is super important. But as you just pointed out, it's not that easy, and there are policies being proposed to try and collect more of that data, but you say that there are, you know, challenges and opportunities there, too. Can you elaborate a little more on that?

BAKER-WHITE: 

Yeah, so we didn't, you know, we were looking at the legislation that's being proposed around IIS, and we're seeing some proposals that kind of expand the role of IIS. So, we wanted to highlight those and think about, you know, the potential impacts that this expansion could have. So, for example, we noted in New York, there was a bill that would require vaccine exemptions to be reported to the IS system. So, you know that could have some value, you know, could give a better picture of the vaccine coverage, could help identify exemption patterns, and you know, maybe, you know, help this help public health, you know, understand, like the reasons why people aren't getting vaccinated or choosing not to be vaccinated.

SHEEHAN: 

So, what should people be watching out for as these policy debates kind of get shaken out in legislatures again?

BAKER-WHITE: 

I think just, you know, looking out for, you know, the reason behind these systems, remembering back to that measles outbreak from the '80s and '90s, and understanding that these systems are there to give us the ability to see the larger picture, they allow us to act efficiently, to act timely, to provide patients with the best information they have, so they can make decisions for their own health. And really, what they do is they protect those at-risk from harm, from the spread of disease. So, I think just, as the policy debates continue, again, just remembering why we have these and the purpose behind them is important.

SHEEHAN: 

Andy Baker-White is ASTHO's senior director of state health policy.

Strong collaboration between public health agencies and health care systems is essential to preparing for and responding to emergency health threats, from supply chain disruptions to large-scale public health emergencies. Coordinated planning helps ensure health care facilities have the resources they need to continue serving their communities. ASTHO sat down with John Lujan, public health emergency preparedness program manager for Guam, to discuss how the jurisdictions guarding the Pacific Conference helped strengthen health care readiness and support response efforts across the unique challenges of the island jurisdictions. Read the full blog post at the link in the show notes.

Laboratory capability is an important aspect of public health emergency preparedness and response. Effective lab testing is critical to successfully detect and understand different public health threats during public health emergencies. On June 29, join ASTHO and APHL for a webinar focused on how health agencies can coordinate with public health laboratories to support emergency response. This webinar will highlight how California coordinated across departments in response to a recent botulism outbreak related to infant formula. Find more information at the link in the show notes.

This has been Public Health Review Morning Edition. I'm John Sheehan for the Association of State and Territorial Health Officials.