A 2-YEAR RANDOMIZED CLUSTER TRIAL TO IMPROVE CHILDHOOD INFLUENZA VACCINATION

Purpose: Although childhood influenza vaccination rates are increasing, they remain below the national goal of 70%, especially among older children.  Few studies designed to increase rates in primary care have been published since the 2008 recommendations to vaccinate all eligible children over age 6 months.  The purpose of this study was to evaluate the success of a multi-strategy, two-year intervention program to raise influenza vaccination rates among children 6 months – 18 years.

Method: In 2011-2013, twenty primary care practices were randomly assigned to Year 1 Intervention and Year 2 Intervention arms of a randomized cluster trial to increase childhood influenza vaccination rates using a toolkit, early delivery of donated vaccine, educational in-service for staff, feedback on rates, and publicity.  In Year 2, the intervention was conducted in the initial control (Year 2 Intervention) sites.  Impact of the intervention in both arms and maintenance of intervention in the Year 1 intervention sites was assessed using t-tests, and multilevel regression modeling in this repeated measures study.

Result: For the Year 1 Intervention group, influenza vaccine uptake increased 12.4 percentage points (PP, P<0.01) during active intervention; uptake was sustained and during maintenance (0.4 PP change), for an overall change of 12.7 PP, increasing from 42.2% to 54.9% (P<0.001).   Influenza vaccine uptake in the Year 2 intervention group increased in both Year 1 (5.2 PP; P<0.01) and in Year 2 (5.9 PP; P<0.01), for an overall change of 11.1 PP (P<0.001), increasing from 46.4% to 57.5%.   Over the 2 years, among 82,395 children, vaccination increased in all practices and significantly (P<0.01) increased in 19 of 20 practices.  Vaccination increased significantly regardless of race and insurance status, and among children over 2 years (P<0.001).  In regression modeling that controlled for age, sex, race, and insurance, likelihood of vaccination was greater in Year 1 than baseline (odds ratio (OR) = 1.35 (95% confidence interval (CI)=1.33-1.38), in Year 2 than Year 1 (OR=1.13 (95%CI=1.11-1.15) and in Year 2 than baseline (OR=1.53 (95%CI=1.51-1.56; P<0.001 for each comparison).

Conclusion: In primary care practices, implementation of a multiple strategy intervention, which included practice improvement toolkit, early delivery of vaccine, feedback on rates and publicity, can significantly improve vaccination rates over two years among children across insurance and racial groups.