As a strong advocate of public health informatics, HLN has spent a lot of time thinking about how data drives policy. But what happens when policy tries to drive the data?
The recent letter from the Centers for Medicare & Medicaid Services (CMS) to state health officers (SHOs) regarding the 2026 updates to the Medicaid and Children’s Health Insurance Program (CHIP) Core Sets of Health Care Quality measures (Child and Adult Core Sets) is more than just an administrative tweak. It is a significant pivot that challenges the progress we’ve made in vaccine equity and immunization quality measures. Here is our take on what this means for the immunization community and why immunization information systems (IIS) are now more critical than ever.
Navigating the Shift: Quality Measures in Flux
Key Measures Impacted
CMS has removed the following immunization measures from the 2026 Child and Adult Core Sets, which provide standardized information that CMS and states can use to evaluate and improve the quality of care that beneficiaries receive:
- Childhood Immunization Status
- Immunization for Adolescents
- Prenatal Immunization Status – for both beneficiaries under age 21 and beneficiaries age 21 and older
States may continue to report these measures voluntarily to CMS; however, CMS has explicitly discouraged states from using these measures in financial incentive arrangements in fee-for-service or managed care plans.
Mandatory reporting requirements that began in 2024 for childhood and adolescent immunization status measures, and the subsequent addition of prenatal immunization status measures, marked important steps toward ensuring Medicaid and CHIP enrollees received life-saving vaccines by enabling greater visibility on vaccine coverage and gaps. Removing these measures from the 2026 Child and Adult Core Sets (Core Sets) risks stalling the momentum toward public health data access and utilization.
The most jarring aspect of the CMS announcement isn’t just the content, but the process—or lack thereof. Traditionally, annual updates to these Core Sets follow a rigorous protocol involving a stakeholder workgroup and a period for public comment prior to issuance of the final measures. This ensures that the measures are evidence-based, actionable, and technically feasible to implement. By bypassing this protocol – which also recently occurred when the Centers for Disease Control and Prevention approved a revised childhood and adolescent immunization schedule based on a decision memo from administration officials – the agency has unilaterally downgraded key immunization measures for reporting in 2026.
The IIS Advantage: Data Resilience Matters
The silver lining to these changes is that the data itself is not going anywhere. States report the CMS immunization measures annually via the Quality Measure Reporting system; pulling data from a variety of existing sources to include administrative claims, Electronic Clinical Quality Measures from electronic health records (EHRs), or most reliably by cross-referencing Medicaid enrollment files with IIS records. Over the last two decades, states have built incredibly robust IIS. These public health systems are powerful sources of vaccine data and the stronghold in helping public health agencies manage outbreaks and pandemics by providing critical information about the immunization status of individuals and insights on populations at risk for vaccine-preventable diseases. IIS do not stop working just because a federal reporting policy changes. Because the data exchange infrastructure for IIS is already so strong, the actual impact of these changes on data collection could be minimal if states remain committed to monitoring and reporting immunization status of Medicaid and CHIP patients.
However, we must be pragmatic in recognizing that these actions taken by the administration are yet another signal of its withdrawal of comprehensive vaccine support, measures, and evidence-based recommendations. This lack of federal leadership in supporting the immunization system in the United States – especially when the country has experienced the most measles cases in 2025 since 1992 and is at risk of losing its measles elimination status – reinforces the importance of states and their immunization programs, along with the responsibility they have to maintain and protect their investments in IIS. Even as the burden of funding and prioritizing these systems falls on state, territorial, and local budgets, it is essential for states to continue modernizing and optimizing their infrastructure to support reporting of key immunization data and measures, particularly as the administration takes its foot off the pedal.
Call to Action: Ensure that IIS Continue Supporting the Public Health Safety Net
The immunization community should not interpret the removal of these measures to be a reduction of importance. In the face of these policy shifts, IIS are even more critical as tools that equip states to understand vaccination coverage in their jurisdictions and potentially across their regions or the nation. IIS, along with the valuable information and features they provide are fundamental to assuring that a strong safety net remains in place – particularly for those at highest risk for vaccine-preventable diseases.
In light of these policy changes, jurisdictions should continue to:
- Report immunization quality measures to CMS and internally monitor their status, even if CMS removes them from the Core Sets. States should maintain the immunization quality measures as requirements for their Medicaid and CHIP delivery systems, if they are already in place.
- Strengthen data sharing and ensure their IIS is fully integrated with Medicaid data systems where possible to provide a clearer picture of vaccination gaps and health disparities.
- Defend the investment in public health by promoting IIS as a vital data source – one that provides data to clinicians and parents to make informed choices related to immunizations.
The biggest risk with CMS’ Core Set changes is not necessarily a loss of existing source data, but a loss of transparency and accountability. When measures are voluntary, states may choose to stop reporting, which could lead to blind spots in the areas where vaccination coverage gaps exist or intervention and advocacy are needed most to ensure that beneficiaries receive the quality, evidence-based care they deserve. By removing immunization quality measures from the Core Sets and explicitly discouraging states from using these measures in financial incentive arrangements, the administration is effectively impeding the ability of important policy levers to help protect children and pregnant women from vaccine-preventable diseases.
As the federal government takes unprecedented actions to shape vaccine policies, the immunization community must recognize that our progress in maintaining high immunization coverage is now even more dependent on state and local jurisdictions, plus health care providers who have historically supported their patients in vaccine decision making. The robust infrastructure of IIS is our greatest asset in this new landscape. We are confident in the continued ability of state and local health leaders, health care providers, other public health advocates, and technology partners to maintain and even increase their commitment to data-driven vaccine decision making. By maintaining immunization quality measure reporting and strengthening the IIS, states can help ensure that the health of their residents – particularly vulnerable populations enrolled in Medicaid and CHIP – remains protected against vaccine-preventable diseases, regardless of shifting federal policies.