A Tale of Two Registries: Unpacking How Strong Immunization Information Systems in New York Helped End the Measles Outbreak

January 29, 2020

The Benefits of Immunization Information Systems to Public Health Efforts 

Immunization Information Systems (IIS) are confidential electronic records of vaccine information which provide a powerful public health tool for patient care, especially during an outbreak.  The benefits of IIS occur on an individual and societal level and include but are not limited to: data usage and collection, timely and accurate patient care, and efficient resource allocation. Access to immunization records allows providers, patients, and some partner organizations, such as schools, to access data in order to inform or notify parties of missing or needed immunizations. 

Utilizing a consolidated data source like an IIS is important given that 20% of children by the age of two have received immunizations from more than one provider, resulting in records that may be fragmented across different health systems or clinics. Such streamlining of health information also supports expanding vaccine access and delivery. 

Most states now use their IIS for ordering and inventory management of public vaccines for programs such as the Vaccines for Children or 317. These vaccines are specifically made available to low-income or under-insured children, uninsured adults or for outbreak control. 

Lastly, local immunization rates calculated from IIS data help provide analyses of vaccine trends nationally and locally, which can then be used to optimize vaccine programs focused on closing gaps and improving coverage rates.   

Getting New York’s IIS’s to Work Together

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In 2008, upstate New York began to consolidate their various individual immunization registries into what is now the New York State Immunization Information System (NYSIIS). This registry covers all areas outside of New York City which, since before 2008, had a registry of its own: the Citywide Immunization Registry (CIR). Despite the potential logistical difficulties with having more than one registry, New York state was proactive in enforcing high registry participation and encouraging data transfer between NYSIIS and CIR in order to compensate for any gaps or shortcomings that could otherwise occur. 

One challenge raised by having multiple registries in the state is with so-called “border children,” whose families live in the counties at the geographical boundaries between NYSIIS and CIR. New York law mandates that, as of January 1, 2008, all current immunizations administered to children less than 19 years of age, along with their histories, must be entered into NYSIIS or CIR within 14 days of administration. Once the data is collected, it is then shared between the two registries, allowing for fewer gaps in information as pertains to these “border children.”

The proactive exchange of immunization records is an effective way to ensure that local schools and healthcare provider offices have access to data that otherwise may be unavailable or difficult to access. Similar efforts to share immunization data also happen between states. For instance, Vermont and New York currently partner to share data, and New Jersey may soon partner in these efforts. When immunization data is made accessible between systems, it increases the ability of records to be fully consolidated. 

IIS Data: The MVP in the Effort to Curb Measles

In September of 2018, New York experienced what would become an outbreak of measles large enough to threaten the United States’ measles elimination status. When presented with the first cases, New York officials were naturally concerned about the scale and future progression of the outbreak. To assess “where they were, and where they needed to be,” health officials required immediate access to accurate, complete and near real-time immunization data, and the IIS provided them a comprehensive picture of vaccine coverage and gaps in outbreak areas.  The registry even allowed health officials to calculate immunization rates within individual zip codes, establishing an essential foundation for containing the outbreak. 

Taking full advantage of New York’s two registries and their relatively high rates of data saturation, public health officials were able to proceed in a systematic manner to address the potential progression and extent of the outbreak. State officials were able to efficiently choose where to dedicate finite resources needed to provide urgent interventions. For instance, officials were able to map zip codes with low immunization rates and establish “pop up” clinics in these specific zip codes to provide emergency doses of the MMR vaccine. 

Further, the state was able to audit schools individually for their immunization rates. When schools lacked data or had incomplete records, referencing the IIS was essential for streamlined collection of immunization information. Since record collection varied widely from school to school, relying on the IIS was essential for resolving ambiguous or inaccurate records within schools. In some cases, the IIS was able to highlight deficiencies in coverage rates, such as when school records showed 100% up-to-date rates, when actual data in the registry more accurately showed around a 70% coverage rate.  

During the New York measles outbreak, health officials greatly benefited from the information housed in their IIS. As immunization registries across the country become more complete with timely, accurate immunization data, their role in outbreak investigation and control will only continue to grow.


Acknowledgments: Immunize Colorado would like to thank NYSIIS for their time and insights, largely making the blog possible. This project is supported by NASHP and the CDC. Any errors, omissions, or conclusions are the author’s.

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