Meta-analysis of effectiveness of interventions to increase influenza immunization rates among high-risk population groups.

Public health interventions have been developed to increase influenza immunization rates among the high-risk elders and patients suffering from cardiopulmonary, metabolic, and other chronic conditions. The relative effectiveness of alternative intervention strategies is not yet well understood. Determination of the most effective strategy should consider characteristics of the target population and the health care delivery system. This meta-analysis of intervention evaluation -studies highlights the importance of considering the baseline immunization rate of the target population in selecting the most effective strategy. While the analysis confirms the feasibility of achieving the 60 percent target coverage established in Healthy People 2000, the results also suggest that as coverage levels increase, single-faceted patient-focused interventions may need to be strengthened by the addition of complementary changes in provider behaviors and/or the delivery system. Further research is needed to identify the most cost-effective combination of intervention strategies, particularly in populations with higher immunization coverage.