Effects of a multi-faceted program to increase influenza vaccine coverage among health care workers: A hospital-based cluster randomized controlled trial

Background: Immunizing health care workers (HCWs) against influenza has proven to protect their patients. Despite recommentations of the World Health Organization and the Dutch Health Council, influenza vaccine uptake among hospital HCWs remains low in the Netherlands Objectives: To assess the effects of implementing a hospital- based multi-faceted influenza immunization program on vaccine coverage in health care workers (HCW) and on patient morbidity. Methods: We conducted a cluster randomized controlled trial among all eight University Medical Centers (UMC) of The Netherlands during the influenza seasons of 2009- 2010 and 2010-2011. Participants were hospital staff of three intervention (n = 27,900 in 2009), three control (n = 22,451) and two external non-randomized intervention UMCs (n = 16,893), and 3,367 patients admitted to the departments of pediatrics and internal medicine during both influenza epidemics. We offered a vaccination implementation progran to staff of intervention and external UMCs, but not to control UMCs. The primary outcome measure was influenza vaccine coverage among HCW. Secondary outcome measures were work absenteeism and patient morbidity. Results: In 2009, the coverage of seasonal, first pandemic and second pandemic vaccine was 32.3%, 61.7% and 45.8% in the intervention UMCs. Corresponding figures for control UMCs were significantly lower at 20.4%, 38.0%, and 17.8%, respectively (p <0.05). In 2010, the coverage of the seasonal vaccine was 28.6% and 17.8% in intervention and control UMCs, respectively (p