Research Articles
Increasing influenza and pneumococcal immunization rates: a randomized controlled study of a senior center–based intervention

https://doi.org/10.1016/S0749-3797(99)00134-8Get rights and content

Abstract

Background: Immunizations decrease morbidity from influenza and pneumococcal infections. Immunization levels remain below desired levels despite clinic-based and public education efforts. This paper describes a randomized, controlled trial of a senior center–based program, which used peer-to-peer outreach to increase pneumococcal and influenza immunization rates among an urban senior population.

Methods: Seniors were randomized to intervention or control groups. The intervention group received educational brochures mailed with reply cards to report immunization status, telephone calls from senior volunteers to unimmunized participants, and computerized immunization tracking. Immunization rates were obtained before and after the intervention by self-report.

Results: Among participants without prior pneumococcal immunization, the pneumococcal immunization rate among the intervention group (52.0%; 95% CI = 46.6%–57.4%) was significantly higher than that of the control group (30.9%; 95% CI = 26.6%–35.2%) (rate ratio = 1.68; 95% CI = 1.40–2.03). Among those without influenza immunization in the prior year, significantly more (50.0%; 95% CI = 40.0%–60.0%) were immunized against influenza in the intervention group than in the control group (23.0%; 95% CI = 15.2%–33.3%) (rate ratio = 2.17; 95% CI = 1.42–3.31). Among those with influenza immunization in the prior year, the rate ratio was 1.04 (95% CI = 1.01–1.07).

Conclusions: The intervention increased both influenza and pneumococcal immunization rates to high levels, suggesting that further progress in increasing adult immunization coverage is possible.

Introduction

Influenza and pneumococcal infections continue to cause significant morbidity and mortality,1, 2, 3, 4, 5, 6 and prevention of these infections remains an important public health activity. The recent emergence of antibiotic-resistant pneumococcus strains adds to the importance of prevention activities.6, 7, 8

Influenza immunization is effective in reducing influenza-related illness, pneumonia, hospitalization, and death among the elderly.9, 10, 11, 12, 13, 14, 15, 16, 17 Influenza immunization of all persons aged ≥65 is recommended by several major advisory groups.18, 19, 20, 21 Although the efficacy of the pneumococcal vaccine in preventing morbidity and mortality from pneumococcal disease has been clearly established only for invasive pneumococcal disease,22, 23, 24, 25, 26 recent evidence supports its use27, 28, 29, 30, 31, 32, 33 and most advisory groups endorse immunization of persons aged ≥65.6, 19, 20

Despite these recommendations, immunization rates are low. In the United States, 66% of seniors reported receiving an influenza immunization in 1996,34 and 45% reported ever receiving a pneumococcal immunization. Multiple factors contribute to low immunization rates, including attitudes of potential vaccine recipients,34, 35, 36, 37, 38, 39 lack of awareness of the vaccines, cost, lack of recommendation by personal health providers,40 and logistical barriers.41

Several clinic or institution-based strategies have increased influenza immunization rates, including patient reminders, immunization tracking systems, standing vaccine orders, distribution of free vaccine to providers, and provision of immunizations at immunization clinics.35, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51 These interventions have not been implemented universally. Additionally, they rely on patients making clinic visits during the influenza immunization season, but the proportion of patients who do so is low.52, 53 These limitations have led to a reported ceiling effect on rates obtainable through clinic-based immunizations in the range of 65%–86%.53, 54, 55, 56 Interventions to increase pneumococcal immunization rates have been less well described and have been primarily hospital-based.48, 57, 58, 59, 60

Therefore, community-based approaches, such as the Medicare Influenza Demonstration Project, may be a useful complement to clinic-based strategies.61 However, this project was resource-intensive, limiting its replicability. Few other reports of controlled trials of community-based programs are available.62

We therefore developed a reminder and tracking system for use by the staff and volunteers of a senior center located in an ethnically diverse, urban community and conducted a randomized, controlled trial of its effectiveness.

Section snippets

Study site and population

The Seattle Senior Immunization Project was conducted under the auspices of Seattle Partners for Healthy Communities and adhered to the principles of participatory action research in its development and evaluation.63, 64 Participatory action emphasizes community participation in project design, in implementation and evaluation, and in shared direction of the project by both researchers and community. The project was based at a senior center in Seattle’s ethnically diverse central area, home to

Results

Of the 5512 persons who were invited to join the project, 1246 (23%) completed the baseline survey and were enrolled in the study (Figure 1). Participants were predominantly White or African American and most had not completed college (Table 1). Nearly all identified a usual source of health care. The characteristics of participants did not differ between the intervention and control groups (Table 1), except that the proportion of intervention group members who reported having received an

Discussion

An intervention consisting of an educational mailing followed by tracking and outreach by senior volunteers was effective in increasing pneumococcal and influenza immunization levels among an ethnically diverse, inner-city group of senior citizens. The intervention had its greatest effect on influenza immunization rates among participants who had not received an immunization in the prior year.

The intervention may have increased immunization rates through increasing the proportions of

Acknowledgements

This project would not have been possible without the generous contributions of many people and agencies, including the Central Area Senior Center senior volunteers, the Central Area Senior Center staff (Carol Allen, Bob Burnside), Senior Services of King County (Terri Kimball, Patricia McInturff, Pamela Owen-Williams), and the Project Advisory Group (Russ Alexander, Carol Allen, Ross Burks, Bob Burnside, Eric Coleman, Mary Davis, Seawellow Holland, Peter Houck, Tom Koepsell, Rachel Pitts,

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    Sources of Support came from the Centers for Disease Control and Prevention Cooperative Agreement U50/CCU011820-02 (Urban Research Centers) and United Way of King County.

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