In this issue of the Journal of Public Health Management and Practice, a number of articles assess coverage and, at the same time, address the usefulness of coverage data from a particular source to answer a particular question-such as using data from Immunization Information Systems (IISs) to cost-effectively improve the administration of the Vaccines for Children program,1 or to improve influenza vaccine use among persons with asthma2; using data from the National Immunization Survey (NIS) to identify potential coverage disparities among children served by public versus private providers3; and using cluster surveys to make certain that the immunization coverage picture is clear in US-affiliated jurisdictions.4

Our current suite of assessment tools and what we assess is strong, but gaps exist. In this editorial, we outline current and future activities.

For preschoolers, the NIS collects provider-validated coverage for all recommended vaccines; state- and city-level estimates are available.5,6 For children, we currently measure influenza vaccination for those aged 36-59 months and those at high risk aged 5-10 years using the National Health Interview Survey; results of this survey are not provider-validated or available by state. For adolescents aged 11-17, national-level, provider-validated results are available from the NIS beginning this year.7 For adults, the National Health Interview Survey provides national estimates and the Behavioral Risk Factor Surveillance System provides state, and some local,8 estimates; both rely on self-report. Additional adult immunization surveys are periodically conducted when more timely or detailed data are needed.9,10 Results on coverage and reasons for nonvaccination for recently recommended adult vaccines from a national survey currently underway will be available by January 2008.

In the eight US-affiliated jurisdictions (Commonwealth of the Northern Mariana Islands, Federated States of Micronesia, Palau, Guam, American Samoa, Marshall Islands, Puerto Rico, and the Virgin Islands), technology limits the use of telephone surveys and registries. Biennial cluster surveys estimate routine vaccination coverage among children (ages 1-2, 6 years) and older adults (age 65+ years). The method employs household interviews with collection of data from immunization records in the home, combined with vaccination histories from hospital records and IISs, where these are in use.

There are some gaps in this portfolio of immunization surveys. For example, research is needed to assess validity of adult self-report of vaccination status, and parental report of child influenza vaccination. Coverage among college students and certain groups of high-risk children and adults is not routinely assessed. No uniform national system measures vaccination at kindergarten entrance, although state-based data in aggregate may provide adequate information on coverage with vaccines recommended during 4-6 years of age.

Local assessments are a must for those who can take action to remedy low coverage. Although selected small-area estimates can be produced using NIS and other large assessment surveys, they cannot produce many of the small-area estimates that are needed. IISs are a promising means of local assessment, but continued progress is needed before they can become a primary tool for either local- or large-area assessment.11 The Centers for Disease Control and Prevention (CDC) is working with two state IISs to evaluate whether they can be used as NIS sample frames, and next year, the CDC will offer a service to states to validate IISs by matching children in an IIS with those sampled by the NIS.

Besides IISs, other local assessment methods include cluster surveys,12,13 random digit dialing surveys,14 birth certificate surveys, and retrospective school surveys.15 Cluster surveys have also been used in the continental United States, and although they are resource intensive, they provide invaluable information, especially in high-risk areas and difficult-to-access communities.12

Another important tool for assessing coverage at the local level is called AFIX-Assessment, Feedback, Incentives, and eXchange of information. This strategy is used at the practice level to overcome an important barrier to raising immunization rates: that providers most often overestimate coverage among the patients in their practice.16 Assessing coverage and assembling practice staff to provide feedback creates the knowledge, concern, and motivation that is required to sustain improved immunization efforts.17 The AFIX approach is currently used in public and private practices, with immunization assessment carried out by state or local health department staff who provide feedback to clinic staff, along with strategies and incentives to raise immunization coverage and information about how vaccine coverage in this practice compares with other practices in the jurisdiction. The assessment component involves a systematic review of a sample of medical records to ascertain vaccination coverage for a defined group of patients and provide diagnostic information.

Strong evidence exists that AFIX works, and is recommended by the Task Force for Community Preventive Services.18,19 In addition, the widespread use of this strategy is supported by its integration into the Vaccines for Children Program federal entitlement program, which provides free vaccine for up to 40 percent of US children.17,20 The AFIX approach has historically been used in the preschool population, but is reportedly being used more widely among adolescent as well as adult clinic populations.

Importantly, for the future of local assessment, AFIX can also play a role. If all providers in a community are assessed, or a representative sample assessed during a period of time, useful information about population coverage could be obtained, at least for children with regular medical care. Indeed, the assessment component of AFIX has been used to calculate rates for an entire community.21 With an appreciation of the limitations of this method, AFIX could be one of the most rapid approaches for assessing uptake of new vaccines.

The CDC has recently embarked on a comprehensive strategic planning process to prioritize changes to vaccination assessment, including an external review panel, an internal CDC workgroup, and input thus far from the National Vaccine Advisory Committee and the Association of Immunization Program Managers. Future plans are to obtain feedback from a broad range of stakeholders, public and private professional organizations, and other advisory groups. As a result of priorities identified so far by the planning efforts, the NIS will be expanded starting in 2008 to provide state- and city-level estimates of adolescent immunization coverage. Society reaps tremendous benefits from its sizeable investment in immunization, and it is crucial to have a robust assessment system to provide timely and high-quality data to continually identify gaps, improve vaccination coverage, provide accountability to the public, and ultimately reduce the health and financial burdens of vaccine-preventable diseases.

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