The following describes the research questions that were identified through a systematic review of population-based interventions designed to increase vaccination coverage among adults, adolescents and children. These questions were published as part of the comprehensive evidence review conducted by the Task Force and published in a special supplement to the American Journal of Preventive Medicine (see Am J Prev Med 2000;18(1S), pp.97-126)

Public health practitioners, policy makers, employers/purchasers, and funders are encouraged to use these findings to help guide research priorities and build a broader evidence base.

RESEARCH ISSUES

Enhancing Access to Vaccination Services

Effectiveness

The effectiveness of recommended and strongly recommended interventions in this section (i.e., reducing out-of-pocket costs, expanding access in healthcare settings as part of multi-component interventions, home visits, and vaccination interventions in WIC settings) is established. However, research issues, which contribute to increased or lessened effectiveness, remain regarding the characteristics of these interventions. For example:

• Are programs to reduce out-of-pocket costs similarly effective among persons who are and who are not economically disadvantaged?
• What are the relative effectiveness and economic consequences of strategies that provide home visits for all persons in a defined population versus those that use staged protocols using less intensive interventions (i.e., reminders) to reach some clients and reserve actual home visits for clients who are hardest to reach?
• What are least- and most-effective combinations of services in multi-component interventions, including multi-component interventions that incorporate increasing access to vaccination services in healthcare settings?
• What are the least- and most-effective combinations of services in WIC interventions?
• How accurate are vaccination data in WIC settings, and how does data accuracy impact effectiveness?

Because the effectiveness of vaccination programs in child care centers, vaccination programs in schools, and single-component interventions to increase access to vaccination in healthcare settings has not been established, basic research questions remain.

• Are these interventions effective in improving vaccination coverage?
• Of the range of strategies that have been used to expand access to vaccination services in healthcare settings, which are the most- and least-useful?
• What attributes of these programs contributes to effectiveness or lack thereof?

Applicability

Each recommended and strongly recommended intervention should be applicable in most relevant target populations and settings. However, possible differences in the effectiveness of each intervention for specific subgroups of the population could not be determined. Several questions regarding the applicability of these interventions in settings and populations other than those studied remain.

• What strategies would be most effective for improving access to vaccinations among adolescents?
• Is effectiveness of WIC interventions in rural areas similar to that described in urban areas?

Other Positive and Negative Effects

In general, studies included in this review did not report on other positive and negative effects of these interventions. Therefore, research regarding the following questions would be useful:

• Do programs to reduce out-of-pocket costs adversely affect development or adoption of new vaccines?
• Do any of these interventions have positive or negative effects regarding subsequent use of primary care?
• Do home visits result in identification of child abuse or neglect?
• Do home visits result in reporting of possible abuse or neglect that is not subsequently confirmed?
• Do WIC interventions result in dropout?
• Do interventions to increase access to vaccinations in healthcare settings interfere with other functions of these settings, and if so, how can this effect be minimized?
• Do these interventions result in other positive changes in use of prevention services or healthcare as well as improving vaccination coverage?

Economic Evaluations

In general, available economic information was sparse. Therefore, considerable research is warranted regarding the following questions:

• What are the costs of these interventions?
• How do costs per additional child vaccinated compare with other interventions to improve vaccination coverage?
• Are home-visiting programs cost-effective relative to other interventions to improve vaccination coverage?
• Can strategies that are designed to improve vaccination coverage and other outcomes concurrently improve cost-effectiveness of these strategies?
• Are home-visiting programs that address more than one issue more or less cost-effective than programs addressing vaccinations only?
• How do specific characteristics of these interventions contribute to economic efficiency?
• What are the relative economic consequences of universal programs to reduce out-of-pocket costs versus programs intended for persons whose need is greatest?
• What combinations of components in multi-component interventions are most cost-effective?
• Are staged home-visit protocols more cost-effective than those that are not?
• What are the most cost-effective combinations of services for WIC programs?
• What is the cost-benefit or cost-utility of these interventions?

Barriers

• How can these interventions be implemented with minimal administrative burden placed on providers or systems and minimal disruption of the settings' primary missions?
• How can reducing out-of-pocket costs be effectively implemented given the fragmentation of payment mechanisms in the United States?
• Can registries help to overcome lack of current immunization status that is sometimes a barrier to implementing these interventions?

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Increasing Community Demand for Vaccinations

Effectiveness

The effectiveness of recommended and strongly recommended interventions in this section (multi-component interventions that include education; client reminder/recall; and vaccination requirements for child care, school, and college attendance) is established. However, research questions regarding the effectiveness of these interventions remain.

• What particular characteristics of interventions to increase community demand for vaccinations contribute to increased or lessened effectiveness?
• How do content, specificity, method of delivery, and frequency of delivery of reminder/recall contribute to effectiveness?
• How do cultural characteristics of clients contribute to increased or lessened effectiveness of different interventions?
• What is the relative effectiveness of reminder and recall systems?
• What are the least- and most-effective combinations of services in multi-component interventions?
• How does the effectiveness of vaccination requirements for child care, school, and college attendance vary by specific requirements of legislation and vigorousness of enforcement?
• Do registries provide a functional backbone for effective interventions, including education or client reminder/recall?

Because the effectiveness of community-wide education-only interventions, clinic-based education only interventions, client or family incentives, and client-held medical records regarding improving vaccination coverage has not been established, basic research questions remain.

• Are these interventions effective in improving vaccination coverage?
• Do these interventions promote positive or negative attitudes toward vaccination among target populations?
• What attributes of clinic-based or community-wide educational programs - medium, message intensity - contribute to effectiveness or lack thereof?
• What attributes of incentives (e.g., type or amount) contributes to effectiveness or lack thereof?
• Do multiple competing prevention messages act in ways that are synergistic or interfering?
• Do client-held medical records reduce missed opportunities for vaccination?

Applicability

Each recommended and strongly recommended intervention should be applicable in most relevant target populations and settings. However, possible differences in the effectiveness of each intervention for specific subgroups of the population could not be determined. Several questions regarding the applicability of these interventions in settings and populations other than those studied remain.

• Are these interventions effective in improving vaccination coverage in adolescents?
• Do meaningful differences exist in effectiveness of these interventions based on the level of scale at which they are delivered (i.e., community-wide systems from a registry versus managed care-based systems versus practice-based systems)?

Other Positive or Negative Effects

With the exception of some discussion of improved use of other clinical and preventive care, the studies included in this review did not report on other positive or negative effects of these interventions. Therefore, research regarding the following questions would be useful:

• Do interventions implemented at the community level (e.g., community-wide education-only interventions or multi-component interventions that include education) result in positive outcomes other than improved vaccination coverage (e.g., community empowerment)?
• Do clinic-based interventions to increase client demand for vaccinations interfere with office flow or efficiency, and if so, how can this effect be minimized?
• Do child care, school, and college vaccination requirements interfere with the other activities of the settings, and if so, how can that effect be minimized?
• Do these interventions result in other positive changes in disease prevention or healthcare as well as improving vaccination coverage?

Economic Evaluations

In general, available economic information was sparse; therefore, considerable research is warranted regarding the following questions:

• What are the costs of these interventions?
• How do the costs per additional child vaccinated compare with other interventions to improve vaccination coverage?
• Can strategies that are designed to improve vaccination coverage and other outcomes concurrently improve cost-effectiveness of these strategies?
• How do specific characteristics of these interventions contribute to economic efficiency?
• What are the relative economic consequences of reminder and recall systems?
• What characteristics of reminders or recall (e.g., frequency, content, or method of delivery) are the most cost-effective?
• What combinations of components in multi-component interventions are most cost-effective?
• What is the cost-benefit or cost-utility of these interventions?

Barriers

• How can these interventions be implemented with minimal administrative burden placed on providers or systems?
• Do community-wide registries reduce barriers to use or increase use of these interventions?

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Provider-Based Interventions

Effectiveness

The effectiveness of recommended and strongly recommended interventions in this section (i.e., provider reminder/recall, provider assessment and feedback, and standing orders) is established. However, research issues regarding the effectiveness of these interventions remain.

• Which characteristics of provider-based interventions contribute to increased or lessened effectiveness?
• How do content and method of delivery of provider reminder/recall relate to effectiveness?
• What components of assessment and feedback interventions (e.g., incentives or benchmarking) contribute most to effectiveness?
• How do different practice settings (e.g., independent private practice settings versus hospital management organization settings) contribute to increased or lessened effectiveness of various interventions?
• What is the effectiveness of HEDIS, as a form of assessment, feedback, and benchmarking, in improving vaccination coverage? In independent private-practice settings? In hospital management organization settings?
• What intermediate outcomes contribute to the effectiveness of provider assessment and feedback (e.g., provider's knowledge, attitudes, or behavior; additional interventions; or other factors)?
• What are the least- and most-effective combinations of services in multi-component interventions?
• Can registries provide a backbone for effective interventions (e.g., provider reminder/recall)?
• How easily can systems for provider reminders or assessment and feedback that encourage the use of one clinical preventive service be adapted for other services?
• What is the relative effectiveness of provider reminders or assessment and feedback that focus on immunizations versus reminders or assessment and feedback that rotate from one clinical preventive service to another?

Because the effectiveness of provider education-only interventions has not been established, basic research questions remain.

• Are these interventions effective in improving vaccination coverage?
• Are these interventions effective in increasing provider knowledge or promoting positive provider attitudes toward vaccination?
• What attributes of provider education-only programs - medium, message, or intensity contribute to effectiveness or lack thereof?
• Are intensive provider education programs more effective than other programs that are less intensive?

Applicability

Each recommended and strongly recommended provider-based intervention should be applicable in most relevant target populations and settings. However, possible differences in the effectiveness of each intervention for specific subgroups of the population could not be determined. Several questions regarding the applicability of these interventions in settings and populations other than those studied remain.

• Are these interventions as effective in improving vaccination coverage in adolescents as they are in children and older adults?
• Do significant differences exist regarding the effectiveness of these interventions based on the level of scale at which they are delivered (i.e., community-wide provider reminders from a registry versus managed care-based systems versus office-practice-based systems)?

Other Positive and Negative Effects

With the exception of some discussion of improved use of other clinical and preventive care, studies included in the review did not report on other positive and negative effects of these interventions. Therefore, research regarding the following questions would be useful:

• Do provider-based interventions to increase vaccination interfere with office flow or efficiency, and if so, how can this effect be minimized?
• Do provider-based interventions result in other positive changes in use of preventive or health care as well as improving vaccination coverage?

Economic Evaluations

Generally, available economic information was sparse; therefore, considerable research is warranted regarding the following questions:

• What are the costs of these interventions?
• How do costs per additional child vaccinated compare with other interventions intended to improve vaccination coverage?
• Can strategies that are designed to improve vaccination coverage be used concurrently with other outcomes to improve cost-effectiveness of these strategies?
• How do specific characteristics of these interventions contribute to economic efficiency?
• What particular characteristics of provider reminder/recall systems contribute most to cost- effectiveness?
• What combinations of components in multi-component interventions are most cost-effective?How do the opportunity costs of multi-component versus single-component interventions compare?
• What is the cost-benefit or cost-utility of these interventions?

Barriers

• How can these interventions be implemented with minimal administrative burden placed on providers or systems?
• Do community-wide registries reduce barriers to use or increase use of provider reminders, provider assessment and feedback, or provider education?
• For provider reminder/recall and provider assessment and feedback, how can the burden on providers (e.g., data entry) be reduced?
• Can improved sampling strategies be developed and can meaningful information be extracted from small samples of records?
• How can the uptake of these interventions in private practices be encouraged?

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