A Randomized Controlled Trial of Elementary School-Located Influenza Vaccination

Background:  School-located influenza vaccination (SLV) programs are increasing, but little evidence exists about their effectiveness in increasing immunization rates.

Objectives: Evaluate the effectiveness of SLV in urban and suburban elementary schools in Monroe County, NY, during fall 2009

Methods: We performed a randomized controlled trial, randomly assigning school districts (stratified by suburban, urban) to one of two SLV interventions versus usual care (no SLV). Intervention schools performed SLV during school hours. Injected and nasal spray seasonal influenza vaccines were offered.  The intervention arms were: Low Intensity (Low= notices+ blank consents mailed to parents in September) and High Intensity (High= Low Intensity intervention+ more frequent notices+ additional blank consents in October+ 2 autodialer reminders).  We assessed influenza vaccination rates in 2008-9 (pre-SLV) and 2009-10 using the NY State immunization information system. We compared intervention vs. control groups using bivariate tests, and odds ratios using a multi-level logistic model to take into account the lack of independence within schools.

Results: In 2008-9 (pre-SLV) influenza vaccination rates were not significantly different by intervention group within suburban or urban schools except Suburban High vs. Low (28% vs 31%, p=.03).  From 8/1/2009 to 1/15/2010 (during SLV) in suburban schools, the proportion vaccinated with >1 dose of seasonal influenza by intervention group was 48% High (n=2195), 46% Low (n=1810), 36% Control (n=1467).  In urban schools, the proportion vaccinated was 38% High (n=2671), 33% Low (n=2351), 26% Control (n=3067).  Uptake was greater for both High and Low vs. controls (p£.01) in all settings, and High>Low in for children attending urban schools (p=0.004).  Controlling for location and grade, overall influenza vaccination rates were higher for High vs control (OR=1.7, p<.001) and Low vs control (OR=1.4, p<.001).

Conclusions: SLV increased influenza vaccination rates significantly, and in urban schools the higher v. the lower intensity intervention was more effective.