Differential proportion of HCW immunization against the seasonal and pandemic influenza in 2009 in a Swiss emergency department

Background: Immunization of health care workers (HCWs) is important to limit the transmission of influenza to patients and to themselves. Seasonal influenza (SI) vaccination of HCWs has been recommended for several decades, but vaccination coverage has remained around 30% at our institution, despite immunization campaigns, provision of free vaccines, and eployment of mobile vaccination teams. In 2009, the vaccination coverage against the pandemic H1N1 influenza (PI) was twice the coverage against SI at our institution, where for the irst time during influenza season, unvaccinated asymptomatic HCWs were required to wear a mask during patient care duties. Objectives: 1) To assess if vaccination coverage against PI followed the same trend in our emergency department (ED) as in the institution; 2) if so, to investigate the reasons of this overage surge. Methods: An anonymous survey was delivered to the 111 nurses and 56 physicians working in our ED in September 2010; 23 questions, based on a literature review, addressed the otential reasons for HCWs to accept or refuse influenza immunization. Additional demographic and professional questions completed the survey, as well as self-reported immunization against both influenza strains. Results are presented as mean and standard deviation, or as proportion; Fisher’s exact test was used to compare proportions; p<0.05 indicated significant differences. Results: Sixty-eight percent of surveys were returned (nurses 79%, physicians 46%, p<0.001). Mean HCW age was 35 ± 9 years; 63% were female. Vaccination coverage was 49% for SI, and 63% for PI (p<0.001); of the HCWs unvaccinated against SI, 40% were immunized against PI, while only 15% of those vaccinated against SI were not vaccinated against PI (p<0.001). the three main reasons for PI immunization were: protection of HCWs families (70%), of their patients (64%), and avoiding wearing a mask (62%). The three main reasons against PI immunization were: preference to wear a mask over immunization (86%), fear of side-effect (57%), and concerns about vaccine safety (57%). Conclusion: In our ED, PI immunization was higher than SI immunization. The majority of HCWs immunized against SI were also immunized against H1N1. PI vaccination rate among SI unvaccinated HCWs increased due to concerns about PI dissemination. Requirement to wear a mask increased immunization coverag