Increasing influenza and pneumococcal immunization rates: A randomized controlled study of a senior center-based intervention

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.