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Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet]. York (UK): Centre for Reviews and Dissemination (UK); 1995-.

Database of Abstracts of Reviews of Effects (DARE): Quality-assessed Reviews [Internet].

Interventions to improve influenza, pneumococcal polysaccharide, and hepatitis B vaccination coverage among high-risk adults: a systematic review

SM Ndiaye, DP Hopkins, AM Shefer, AR Hinman, PA Briss, L Rodewald, and B Willis.

Review published: 2005.

Link to full article: [Journal publisher]

CRD summary

This review concluded that provider reminder systems (alone) and combination interventions (enhanced access with provider/system-based interventions and/or increased client/community demand for vaccinations) were effective in increasing target vaccination coverage. The conclusions reflected the evidence presented, but limitations of the evidence made the applicability of the results unclear for one specific vaccination type, or for healthcare systems outside the USA.

Authors' objectives

To evaluate the effectiveness of interventions to improve vaccination cover in targeted high-risk populations.


Search methodology was reported in detail in a previously published article (see Other Publications of Related Interest). MEDLINE, EMBASE, PsycLIT, Sociological Abstracts, CAB Health, HealthSTAR, AIDSLINE, Occupational Safety and Health Database, Educational Research Index, PsycINFO, Dissertation Abstracts, and Conference Papers Index were searched for studies in English from 1980 and August of 2001. Reference lists of retrieved papers were searched and experts consulted.

Study selection

Primary studies that evaluated interventions to improve vaccination coverage of influenza, pneumococcal polysaccharide infections and hepatitis B in individuals (aged 65 years and under) at a high risk for infection, morbidity, or mortality, compared with an unexposed or less-exposed population, were eligible for inclusion. Studies had to be conducted in an established market economy, and measure differences or changes in vaccination coverage. Simple before-and-after comparisons, cross-sectional surveys, and post-only study designs were excluded.

Interventions were classified as: increased demand (client education, reminders and incentives); provider or system-based (standing orders and provider education, reminders and feedback); or enhanced access (increased access and reduction in out-of-pocket costs). Most studies evaluated the uptake of the influenza vaccine. Only three studies were conducted outside of North America; two in The Netherlands, and one in Switzerland.

It seemed that study selection was conducted by two reviewers, with differences being resolved by consensus.

Assessment of study quality

Study quality was assessed in terms of nine limitations: descriptions of populations and interventions, sampling, exposure and outcome measurement, data analysis, interpretation of results, and other (not defined). Studies were classified as good (0 or 1 limitation), fair (2 to 4 limitations) or limited (5 or more limitations) quality; studies of limited quality were excluded from the analysis.

Two reviewers assessed study quality; differences were resolved by consensus.

Data extraction

The mean difference or post intervention difference between treatment and control arms were extracted from controlled studies, and change from baseline from before-and-after studies, by two reviewers; differences were resolved by consensus. The authors stated that data were collected for other health and non-health effects of the interventions; specific details not provided.

Methods of synthesis

Studies were combined in a narrative synthesis; median and range change in percentage vaccination coverage were reported. Differences between studies were discussed in the text and study details tabulated.

Results of the review

Thirty-three studies (across 35 comparisons) met the inclusion criteria (over 72,095 participants; range 195 to 35,316). Twelve comparisons were of single interventions to increase target vaccine coverage, and 23 were of a combination of interventions. Of the studies of combination interventions, 20 included interventions to increase demand, 14 included provider or system-based interventions, and 19 included enhanced access interventions. Eighteen comparisons were randomised trials, four non randomised trials, four other designs with a concurrent comparison group, six time series and four were retrospective cohort studies. One comparison was classified good for quality of execution; the others were classified as fair. Where reported, most studies had follow-up of one year or less (range two months to 10 years).

The only intervention evaluated alone that showed strong evidence of effectiveness for increasing targeted vaccination coverage was provider reminder systems (median improvement 17.9 percentage points, range -1 to 72; seven studies); most of the other interventions of interest had not been evaluated, or were evaluated in only one or two studies.

The combination of interventions that showed strong evidence of effectiveness for increasing targeted vaccination coverage was enhanced access to vaccination services plus provider- or system-based interventions and/or interventions to increase client or community demand for vaccinations (median improvement 16.5 percentage points, range -5.9 to 67; 16 studies).

Cost information

Economic evaluations were sought; none relevant to the review question were identified.

Authors' conclusions

Strong evidence was identified of the effectiveness of provider reminder systems (implemented alone) and a combination of interventions (enhanced access to vaccination services plus provider- or system-based interventions and/or interventions to increase client or community demand for vaccinations) in increasing target vaccination coverage.

CRD commentary

The review addressed a clear question supported by appropriate inclusion criteria. However, it was unclear how consistently the criteria were applied due to the limited details provided for the included studies. 'Simple' before-and-after comparisons were excluded, but the definition of simple in this context was not given; some before-and-after comparisons seemed to be eligible. The authors stated that studies had to recruit people aged 65 years and over, and at high risk, but it was not clear that all the included studies met this criteria. Several relevant sources were searched, but only English language studies were included, so language bias could not be ruled out. Each stage of the review seemed to have been conducted in duplicate, reducing the potential for error and bias.

Study quality was assessed using appropriate criteria; the methodological quality of the included studies was limited. The decision to combine studies in a narrative synthesis seemed appropriate; there was no stratification by type of vaccination. Although the interventions indicated in the authors' conclusions were those with the largest volume of evidence, the quality of the included studies was not high, so the strength of the evidence base may have been overestimated. In addition, data for the different types of vaccination were combined and the vast majority of the studies were conducted in the USA. Therefore, it is unclear how generalisable the results would be to one specific type of vaccination, or to countries with healthcare systems outside of the USA.

Implications of the review for practice and research

Practice: The authors did not make any specific recommendations for practice.

Research: The authors identified a large number of outstanding research questions relating to the effectiveness of available interventions, different high risk subgroups, different settings, barriers to implementation of vaccination and cost-effectiveness.


Not stated.

Bibliographic details

Ndiaye SM, Hopkins DP, Shefer AM, Hinman AR, Briss PA, Rodewald L, Willis B. Interventions to improve influenza, pneumococcal polysaccharide, and hepatitis B vaccination coverage among high-risk adults: a systematic review. American Journal of Preventive Medicine 2005; 28(5 Supplement): 248-279. [PubMed: 15894160]

Other publications of related interest

Ndiaye S M, Hopkins D P, Smith S J, Hinman A R, Briss P A. Interventions Methods for conducting systematic reviews of targeted vaccination strategies for the guide to community preventative services. American Journal of Preventive Medicine 2005;28(5 Supplement):238-247.

Briss P A, Zaza S, Pappaioanou M, Fielding J, Wright-De Aguero L, et al. Developing an evidence-based guide to community preventative services - methods. American Journal of Preventive Medicine 2005;18(1 Supplement):35-43.

Indexing Status

Subject indexing assigned by NLM


Adult; Aged; Communicable Disease Control /methods /standards; Evidence-Based Medicine; Health Planning Guidelines; Health Promotion /methods /standards; Health Services Accessibility; Hepatitis B Vaccines /administration & dosage; Humans; Immunization Programs /methods /standards; Influenza Vaccines /administration & dosage; Middle Aged; Pneumococcal Vaccines /administration & dosage; Program Evaluation; Public Health Administration /methods /standards; Reminder Systems



Database entry date


Record Status

This is a critical abstract of a systematic review that meets the criteria for inclusion on DARE. Each critical abstract contains a brief summary of the review methods, results and conclusions followed by a detailed critical assessment on the reliability of the review and the conclusions drawn.

CRD has determined that this article meets the DARE scientific quality criteria for a systematic review.

Copyright © 2014 University of York.

PMID: 15894160


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