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State immunization information systems (IIS), also known as immunization registries, are population-based databases that record vaccinations administered by participating health care providers in a given state (1). Most states require providers to report certain vaccinations—frequently childhood immunizations—to their state’s IIS (2). IIS also became more commonly used to record adult vaccinations during the COVID-19 pandemic. Primary care physicians (PCPs), in particular, play a key role in administering and reporting immunizations to IIS, which are an important source of information for parents and the general public, as well as for assisting public health authorities with resource allocation, identifying populations at-risk for vaccine preventable disease, and informing programs to increase vaccination coverage (3). PCPs also benefit from the information available in IIS, which enable access to patients’ complete vaccination history and can help flag when patients are due for recommended vaccines. This data brief uses data on PCPs from the 2022 National Physician Health IT Survey to describe PCP satisfaction with their electronic access to external immunization information in their electronic health record (EHR) system and/or portal outside the EHR, and methods used to view immunization data from outside sources. This brief also describes PCPs’ awareness of their EHR’s capabilities to electronically report data to and access data from the IIS.
Figure 1: Primary care physicians’ satisfaction with their electronic access to immunization information in their EHR and/or portal outside the EHR

Figure 2: Method(s) primary care physicians reported using to view immunization data from outside their organization

Figure 3: Primary care physicians’ satisfaction with their electronic access to immunization information, by method of viewing immunization data from outside organizations.

Table 1: Primary care physicians’ use of an EHR to view immunization data from outside organizations, by practice characteristics
| Practice Characteristics | % PCPs who use an EHR to view data |
|---|---|
| Main Setting | |
| Private or group practice, freestanding clinic or urgent care (N = 460) ref | 36% |
| Integrated Delivery System, HMO, health system or other prepaid practice (N = 117) | 58%* |
| Academic health center or faculty practice (N = 429) | 47%* |
| Hospital outpatient department (N = 114) | 45% |
| FQHC or Look-Alike or Rural Health Clinic (N = 166) | 40% |
| Other (N = 89) | 23%* |
| Practice Size | |
| 1 to 3 physicians (N = 279) ref | 27% |
| 4 to 10 physicians (N = 401) | 41%* |
| 11 to 50 physicians (N = 338) | 47%* |
| More than 50 physicians (N = 354) | 47%* |
| Value-based Care Participation | |
| Yes (N = 1,027) ref | 45% |
| No (N = 168) | 23%* |
| Don’t know (N = 179) | 33%* |
| EHR vendor | |
| Epic (N = 743) ref | 59% |
| Cerner (N = 123) | 37%* |
| eClinicalWorks (N = 88) | 31%* |
| athenahealth (N = 76) | 32%* |
| Other (N = 344) | 25%* |
| Region | |
| Midwest (N = 349) | 42%* |
| Northeast (N = 272) | 44%* |
| Southeast (N = 264) | 35% |
| Southwest (N = 106) ref | 28% |
| West (N = 384) | 47%* |
Figure 4: Primary care physicians’ awareness of their EHR’s capabilities to access data from or report data to their state’s IIS (among those who use an EHR to view immunization data).

Physician access to IIS data via their EHR or IIS portal outside the EHR enables quick and easy access to a patient’s full immunization history, helps keep track of a patient’s immunization status, and provides access to broader population data that can aid in clinical decision-making (4). Such access has been shown to improve vaccination rates, especially when used in tandem with clinical decision support tools integrated with the EHR to prompt physicians or office staff when a patient’s vaccinations are due (5,6). EHR-IIS connectivity is particularly important as it eliminates the burden of signing into a separate portal to access immunization data and helps ensure that patient immunization records are accurate and complete (7).
In 2022, more than half of PCPs (58%) reported satisfaction with their electronic access to external immunization information in their EHR or portal outside the EHR. However, only 21% were “very” satisfied and more than one-third of PCPs (36%) reported being “not at all” satisfied with their electronic access to this information. An analysis of these same questions in the 2022 American Board of Family Medicine (ABFM) Continuous Certification Questionnaire (CCQ) found similar levels of satisfaction among family medicine physicians (see Appendix Table A4). Overall satisfaction was highest among PCPs who viewed immunization data in their EHR (75%), followed by those who view immunization data via a portal outside the EHR (62%). Taken together, these findings suggest improving EHR-IIS connectivity—which would enable physicians to view immunization data in their EHR rather than an outside portal—would likely increase physician satisfaction with access to external immunization information. About 10% of PCPs do not have any access to immunization information from outside organizations but would like some type of access.
The share of PCPs who viewed immunization data from outside organizations in their EHR (41% overall) varied by practice characteristics. For instance, PCPs practicing in an integrated delivery system, HMO, health system or other prepaid practice (58%), as well as those in an academic health center or faculty practice (47%), reported the highest rates of viewing outside immunization data in their EHR compared to other practice settings. Further, PCPs working in larger practices and those participating in value-based care had higher rates of viewing external immunization data in their EHR (41 to 47% and 45%, respectively) compared to those working in smaller practices and not participating in value-based care. PCPs using Epic as their primary EHR vendor reported using their EHR to view immunization data from outside organizations at significantly higher rates (58%) than PCPs using other EHR vendors, including other leading vendors, Cerner (37%) and eClinicalWorks (31%). Reported rates of using an EHR to view immunization data from outside organizations varied regionally which may be due, in part, to regional differences in EHR vendor market share (see Appendix Table A5). For instance, PCPs in the Southeast and Southwest regions had significantly lower rates of using Epic—the leading EHR vendor by market share—who enables IIS-EHR connectivity. Regional differences may also reflect state-level variation in EHR vendor or IIS capabilities that we were unable to examine due to small samples in certain states.
In 2022, about three-quarters of PCPs who viewed immunization data in their EHR indicated they were aware their primary outpatient EHR was capable of electronically accessing immunization data from (77%) and reporting data to (74%) their state’s IIS. As a point of comparison, family medicine physicians who used an EHR to view immunization data reported similar capabilities of their EHR to access and report data to the IIS (Appendix Table A4). However, rates varied by primary care sub-specialty with pediatricians having the greatest awareness of their EHR’s capabilities to access data from or report data to their state’s IIS (see Appendix Table A3). This variation likely reflects differences in patient populations served as well as differences in reporting requirements for these populations (e.g., many states require reporting for child and adolescent vaccinations but not for adult populations). It is worth noting, however, that reported capabilities do not necessarily represent the actual capabilities of PCPs’ EHRs to report data to or access data from a state IIS. About 1 in 5 physicians who viewed immunization data through their EHR reported being unaware of their EHR’s IIS access (16%) and reporting (23%) capabilities, with certain primary care sub-specialties having higher rates of unawareness. Further research comparing PCP-reported capabilities to actual EHR capabilities would provide more insight into these differences and potential drivers. Variation in state laws around IIS reporting and opt-in vs. opt-out policies for patients may also drive some of the observed differences in providers’ awareness or use of their EHR’s access and reporting capabilities.
Several early and ongoing efforts have contributed to the current state of EHR-IIS connectivity, which requires providers to possess EHRs capable of connecting to IIS and for IIS to have the capacity to accept the connection and exchange immunization information. The Centers for Medicare & Medicaid Services’ (CMS) Promoting Interoperability (PI) performance category for Merit-Based Incentive Payment System (MIPS) eligible clinicians has been an important means of incentivizing provider reporting to IIS. Immunization registry reporting was an early requirement for eligible clinicians participating in the Medicare Meaningful Use Program (the early version of the PI program), and in 2022, became required again for MIPS eligible clinicians to encourage adoption and use of ONC-certified EHRs that are capable of transmitting data to immunization registries according to specified standards and implementation specifications aimed at promoting interoperability between EHRs and IIS (8,9,10).
On the public health side, the Centers for Disease Control and Prevention (CDC) in partnership with the American Immunization Registry Association (AIRA), the Health Information Management Systems Society (HIMSS), and the Drummond Group developed the Immunization Integration Program with the goal of improving immunization data interoperability and providing a means of testing EHR capabilities to exchange with IIS. Further, CDC’s National Center for Immunization and Respiratory Diseases (NCIRD), in partnership with AIRA, developed the Measurement and Improvement Initiative to assess IIS alignment with IIS Functional Standards which describe the technology needed for IIS to support vaccination providers and other immunization stakeholders.
Collectively, these efforts aim to encourage health IT developers to implement capabilities in their products to support immunization information exchange, incentivize immunization registry reporting among providers, and facilitate EHR-IIS connectivity. Our findings indicate that PCPs who used an EHR to view immunization data had the highest rates of satisfaction with their electronic access to immunization information and tended to report their EHR can access data from and report data to their state’s IIS. These findings demonstrate the overall success of efforts to promote interoperability of immunization information but also highlight room for improving EHR-IIS connectivity and PCP satisfaction with their access to external immunization information. With CDC’s Data Modernization Initiative efforts underway, improving interoperability of EHR and IIS systems could help improve physicians’ ability to report, access, and view immunization information needed to support patient care and population health. It will be important to work closely with federal partners to evaluate and maintain efforts to increase access and reporting to IIS.
Data are from the 2022 National Physician Health IT Survey, a nationally representative survey of office-based physicians. TheUniversity of California San Francisco (UCSF) in partnership with ONC and the American Board of Family Medicine (ABFM), surveyed U.S. outpatient physicians across specialty areas recruited from the Definitive Healthcare Physician Database. The survey was fielded April to November 2022, yielding a sample of 3,006 physicians who provided outpatient care and used an EHR (3.6% response rate). Analyses in this brief were restricted to primary care physicians (N = 1,375) which included the following sub-specialties: Family medicine (N = 448), Internal medicine, (N = 348), Obstetrics/Gynecology (N = 206), Pediatrics (N = 340), and other (N = 33). Results were weighted to account for non-response and generate national estimates.
The authors are with the Office of Technology, within the Office of the National Coordinator for Health Information Technology (ONC). The data brief was drafted under the direction of Mera Choi, Director of the Technical Strategy and Analysis Division, Vaishali Patel, Deputy Director of the Technical Strategy and Analysis Division, and Wesley Barker, Chief of the Data Analysis Branch with subject matter expertise from Rachel Abbey, Kathleen Tully, and Molly Murray.
Richwine C, Strawley C. Electronic Access to Immunization Information among Primary Care Physicians. ONC Data Brief [Internet]. 2024 April; data brief 70.
Appendix Table A1: National Physician Health IT Survey Questions
| Survey Questions | Response Options |
|---|---|
| Rate your current satisfaction with accessing the following types of external patient information electronically (within your EHR and/or portal): Immunizations | Not at all satisfied / Somewhat Satisfied / Very Satisfied / Don’t have/use it |
| Does your primary outpatient EHR electronically: (1) Report immunization data to your State’s immunization information system (IIS)? (2) Access immunization data from your State’s IIS? | Yes / No / Don’t know / Not available |
| How are you able to view immunization data from outside of your organization? Check all that apply. | In a primary outpatient EHR / In an electronic portal outside the EHR (e.g., to an IIS or Health Information Exchange) / Other / I can’t view these data / Don’t know |
Appendix Table A2: Method(s) primary care physicians use to view immunization data from outside their organization and satisfaction with access to immunization information, by method.
| View Method | % Method(s) used to view immunization data | % PCPs satisfied with access |
|---|---|---|
| Use only one method to view data: | ||
| Primary outpatient EHR only (“EHR”) (N = 376) | 24% | 75% |
| Electronic portal outside the EHR only (“Portal”) (N = 249) | 21% | 53% |
| Other methods (e.g., paper, fax) only (“Other”) (N = 99) | 9% | 45% |
| Use multiple methods to view data: | 22% | 71% |
| EHR & Portal (N = 124) | 9% | 80% |
| EHR & Other (N = 48) | 3% | 59% |
| Portal & Other (N = 63) | 5% | 56% |
| EHR, Portal, & Other (N = 76) | 5% | 76% |
| Can’t view these data (N = 177) | 14% | 37% |
| Don’t know (N = 160) | 10% | 48% |
Appendix Table A3: Primary care physicians’ awareness of their EHR’s capabilities to access data from or report data to their state’s IIS (among those who view data in their primary outpatient EHR), by primary care sub-specialty
| Panel A: Access data from IIS? | Yes | No | Don’t know or N/A |
|---|---|---|---|
| All primary care | 77% | 7% | 16% |
| Family Practice (N = 207) | 79% | 8% | 14% |
| Internal Medicine (N = 170) | 78% | 7% | 15% |
| Obstetrics/Gynecology (N = 69) | 56% | 5% | 39% |
| Pediatric Medicine (N = 163) | 83% | 7% | 11% |
| Other (N = 15) | 74% | 26% |
| Panel B: Report data to IIS? | Yes | No | Don’t know or N/A |
|---|---|---|---|
| All primary care | 74% | 4% | 23% |
| Family Practice (N = 207) | 75% | 4% | 20% |
| Internal Medicine (N = 170) | 70% | 6% | 24% |
| Obstetrics/Gynecology (N = 69) | 44% | 5% | 50% |
| Pediatric Medicine (N = 163) | 87% | 1% | 12% |
| Other (N = 15) | 63% | 37% |
Appendix Table A4: Comparison of Primary Care and Family Medicine Physician Survey Data
| Panel A: Satisfaction with access to external immunization information electronically (within the EHR and/or portal): | Primary Care | Family Medicine |
|---|---|---|
| Very Satisfied | 21% | 27% |
| Somewhat Satisfied | 37% | 45% |
| Not at all Satisfied | 36% | 23% |
| Don’t have/Don’t use it | 5% | 5% |
| Panel B: Methods of viewing immunization data from outside organizations | Primary Care | Family Medicine |
|---|---|---|
| In primary outpatient EHR | 41% | 44% |
| In an electronic portal outside the EHR | 40% | 40% |
| Other (e.g., paper or fax) | 22% | 18% |
| I can’t view these data | 15% | 11% |
| Don’t know | 10% | 12% |
| Panel C: EHR capabilities to access data from their state’s IIS(among those who view data in their primary outpatient EHR) | Primary Care | Family Medicine |
|---|---|---|
| Yes | 77% | 76% |
| No | 7% | 8% |
| Don’t know | 16% | 15% |
| Not available | 0% | 1% |
| Panel D: EHR capabilities to report data to their state’s IIS(among those who view data in their primary outpatient EHR) | Primary Care | Family Medicine |
|---|---|---|
| Yes | 74% | 77% |
| No | 4% | 6% |
| Don’t know | 22% | 16% |
| Not available | 1% | 0% |
Appendix Table A5: Primary care physician EHR vendor market share, by region.
| Physician Characteristics | Epic (N = 743) | Other (N = 631) |
|---|---|---|
| Region | ||
| Midwest (N = 349) ref | 42% | 58% |
| Northeast (N = 272) | 45% | 55% |
| Southeast (N = 264) | 30%* | 70%* |
| Southwest (N = 106) | 25%* | 75%* |
| West (N = 384) | 43% | 57% |
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