A questionnaire was sent to 79 of a total of 81 hospitals. Eventually, the questionnaire was returned by 42 hospitals (52% response rate). The size of the hospitals ranged from 600 to 5,500 health care workers. The average vaccination rate for influenza in this sample was 17.7% (median value 16.0%, minimum 0.5% and maximum 45.4%, 95% CI 14.6% to 20.8%).
Health care workers were invited for influenza vaccination personally by mail in 26% of hospitals, and 100% used general written information for all health care workers. Only 3% organized information meetings about influenza vaccination. In all, 100% of the hospitals supplied their health care workers with influenza vaccination free of charge. Vaccines were administered at the departments in 58% of hospitals, 84% had mobile carts, 97% had a central location to administer vaccines and only 4% vaccinated at special request.
As shown in Table , the majority of management of hospitals agreed with the first three items (vaccination effects mortality and both health care workers and hospital managements have a special responsibility in protecting patients and offering vaccination). Thirty of the 42 hospital administrators (71.4%) believed that vaccinating against influenza has an effect on mortality of patients in the hospital. However, when vaccination rates remain too low only three hospitals (7.1%) would consider implementing a mandatory vaccination program.
Agreement of hospital management on questions concerning influenza vaccination (N=42)
Half of the hospital managements thought that an intervention program could raise the vaccination rate. Further, 19 administrators (45.2%) believed that an intervention program would have a positive effect on vaccination rate. Management of 29 hospitals (69.0%) believed that the vaccine is effective against influenza.
In Table is shown how the factors were related to the average vaccination rate. When health care workers are personally informed about influenza vaccination, the average vaccination rate is somewhat higher than any other form of providing information (18.9% compared to 15.6%, 95%CI −2.97% to 9.70%). The managements’ positive beliefs about the effect of vaccination on mortality of patients was associated with an average vaccination rate of 19.0% compared to 16.7% when there were negative beliefs about this effect.
Agreement of management of hospitals (N=42) with possible predictors of vaccination rate and mean vaccination rate
In hospitals where management agreed to be responsible for offering the vaccine to health care workers an average vaccination rate of 18.8% was observed opposed to 10.0% in hospitals in which management disagreed with being responsible.
In all, 11 out of 42 hospital management believed mandatory vaccination will reduce costs. Of these hospitals, the ones that agreed had an average vaccination rate of 16.7% and the ones that disagreed had an average vaccination rate of 15.6%. When asked if they wanted to implement a mandatory vaccination only three hospitals were willing to do so.
The costs of the annual flu campaign and the actual vaccination differed a lot between general hospitals. The average costs for the annual influenza vaccination campaign in 2010 were €640.38 per hospital with a minimum of €0.00 and a maximum of €2000.00 (standard deviation 563.21). The average costs for vaccination were €4198.54 per hospital with a minimum of €0.00 and a maximum of €14262.50 (standard deviation 3643.61).
In Figure the costs of the vaccination campaigns are compared to the vaccination rate, showing a higher vaccine uptake among HCWs in hospitals which spent more money on their vaccination campaign. To assess if a more expensive influenza campaign is correlated with a higher vaccination rate an independent t-test was performed. Only four hospitals spent more than €1250 on the influenza campaign. The average vaccination rate of these hospitals was 24.0% compared to 15.0% of hospitals that spent less than €1250 (mean difference 8.97; p<0.05), demonstrating a higher vaccine uptake among HCWs in hospitals which spent more than €1250 on their vaccination campaign. These differences remained if analyzed according to size of the hospital (25% versus 18% in hospitals with less than 2,000 health care workers and 23% and 14% in hospitals with more than 2000 health care workers).
Average vaccination rate at different cut-off points of influenza campaign costs in Euros.N=25 (vaccination rate in %).