Immunization registries: an essential tool for measles elimination in Canada

Key points

• Canada’s ability to effectively manage and control its current multijurisdictional measles outbreak is impeded by a lack of a national network of interoperable immunization registries, among other challenges.

• Recent measles outbreaks in other countries, along with Canada’s experience during the COVID-19 pandemic, have shown that immunization registries are feasible and critical to an effective outbreak response.

• During outbreaks, immunization registries allow providers to identify those who are underimmunized, assess individuals’ measles susceptibility for postexposure prophylaxis, minimize days missed from school or work owing to illness or quarantine, and reduce health care expenditures by preventing secondary cases.

• Immunization registries that provide timely access to real-time, individual-level immunization data for all health care providers and their patients will be essential for reverifying and sustaining Canada’s measles elimination status.

In November 2025, Canada lost its measles elimination status, which it had held since 1998.¹ From October 2024 to November 2025, more than 5000 measles cases associated with a large multijurisdictional outbreak were reported in 10 provinces and territories, after the introduction of measles into underimmunized communities.² The outbreak has been declared over in some regions² but continues in others, which has put substantial pressure on health systems and highlighted several challenges in Canada’s public health system. The lack of a national network of interoperable immunization registries is one such challenge. To regain measles elimination status, Canada must demonstrate that endemic measles transmission has been interrupted for at least 12 consecutive months, strong surveillance systems are in place, and immunization coverage above the 95% threshold needed to interrupt transmission has been achieved across all communities.^1,3,4 We discuss the role of immunization registries as critical tools for effectively managing and controlling outbreaks of vaccine-preventable diseases like measles and regaining measles elimination status in Canada.

Immunization registries are secure, confidential, electronic information systems that collect and consolidate immunization records. Under Canada’s federated health care system, provinces and territories are responsible for immunization program delivery and surveillance. They have different systems and legislation in place to record vaccinations, which affects the comprehensiveness and quality of the data available in immunization registries in Canada.^5,6 Provinces and territories also differ with respect to their publicly funded immunization schedules, types of health care providers who provide vaccines, and settings where vaccines are given. Many clinicians record immunizations in their patients’ electronic medical records, but these systems are often not accessible to other providers or people who wish to access their own vaccination information, and they do not routinely feed into public health information systems in most provinces and territories. Although most Canadian jurisdictions report measles immunization coverage generally above 80%,⁷ coverage is not uniformly high within regions. Many people in Canada still rely on a paper-based card that too often serves as their only record of vaccination — for example, Ontario’s immunization registry is largely based on parental self-report for school-aged children.⁵ Some provinces, like Alberta and Manitoba, have more comprehensive immunization registries and may be better able to track administered vaccine doses in real time, accurately estimate small-area coverage, identify pockets of low coverage that are driving local outbreaks, build relationships and prioritize targeted interventions in underimmunized communities, and model disease spread. Such information, along with rapid public health responses, strong surveillance systems, and political commitment will be needed to support Canada’s measles reverification.^1,4

Measles outbreaks are costly and resource intensive. During outbreaks, immunization registries allow health care providers to offer missed doses to underimmunized patients proactively, alleviate the substantial public health administrative resources needed to track down immunization records, and free up capacity for case and contact management for those at highest risk of measles and its complications. They can facilitate assessments of susceptibility for timely postexposure prophylaxis after an exposure, minimize days missed from school or work owing to illness or quarantine, and reduce health care expenditures by preventing secondary cases. Beyond the current outbreak, immunization registries improve continuity of care and reduce the costs of unnecessary health care visits.^5,6 From a public health perspective, registries enable targeted vaccine use during periods of limited supply and allow providers to offer accelerated vaccination schedules or additional vaccine doses during outbreaks, while evaluating the impact of these strategies on coverage and the outbreak’s trajectory in real time.

Jurisdictions outside Canada have shown that immunization registries are critical to an effective outbreak response. In a large measles outbreak in the Netherlands from 2013 to 2014, the national immunization registry was used to identify municipalities with low measles immunization coverage and provide early vaccination to more than half of eligible infants.⁸ In the 2018 to 2019 New York City measles outbreak, the Citywide Immunization Registry was used to contact unimmunized children and evaluate the outbreak vaccination strategy, revealing that the number of infections and hospital admissions would have been 10 times higher without vaccination.^9,10 Similarly, Israel’s national immunization registry was used during the 2018 to 2019 outbreak to identify unvaccinated children, which led to marked declines in measles cases in affected neighbourhoods within 3 months.¹¹ In both the New York and Israel outbreaks, immunization registries contributed to increasing coverage by about 10% to 15%, notably in underimmunized groups, through community vaccination strategies, offering important lessons for Canada.^9,11

Over the last 3 decades, calls to strengthen Canadian public health surveillance systems and immunization registries have increased, including recent reports from the Ontario Immunization Advisory Committee and Canada’s chief public health officer. ^5,6 During the COVID-19 pandemic, provinces and territories rapidly implemented scalable, adaptable systems that were used to inform Canada’s public health response to COVID-19 and evaluate immunization strategies in real time.^5,6 For the first time in many jurisdictions, front-line clinicians and individuals had timely access to real-time, individual-level digital immunization records. Although some progress has been made in leveraging these purpose-built systems since the pandemic and modernizing existing data systems, barriers to the implementation of immunization registries remain.^5,6 Strong leadership, ongoing funding, and interprovincial collaboration will be required for Canada to realize a national network of interoperable registries.

Reverifying and sustaining Canada’s measles elimination will require coordinated efforts among health care providers and public health practitioners to drive immunization coverage above the measles immunity threshold, reduce inequalities in vaccine uptake and access, and strengthen public health surveillance systems, including through the expanded use of electronic immunization registries. The COVID-19 pandemic showed that it was possible to establish immunization registries in Canada, and the current measles outbreak demonstrates why these efforts are now imperative.

Registries should adopt standard data elements and terminology and be interoperable, allowing for the exchange of data at local, provincial, and national levels. This aligns with Canada’s renewed 2025–2030 Interim National Immunization Strategy and initiatives under way such as the Joint Federal, Provincial, and Territorial Action Plan on Health Data and Digital Health. Immunization registries will require ongoing investment and political will, but will be instrumental for supporting data-driven approaches to prepare for future outbreaks and regain Canada’s measles elimination status.