Vaccination against pandemic influenza A H1N1 among health care workers. Lessons for the next pandemic.

T World Health Organization (WHO) declared the first influenza pandemic of the 21st century in June 11, 2009.1 As a consequence of the preparedness of the international health authorities for an influenza pandemic, a safe and effective vaccine was ready for use in October 2009, while the pandemic was at an early stage in the Northern Hemisphere. As stated by WHO, health care workers (HCWs) are one of the priority groups for pandemic vaccination due to their critical role in maintaining vital healthcare structure. Many countries including Turkey, advocated the national vaccination campaigns starting with HCWs. Unfortunately, influenza A/H1N1 vaccine uptake rates of HCWs remained very low in many countries.2-4 The Turkish Ministry of Health started vaccination of HCWs on November 2, 2009. Vaccination against influenza A/H1N1 was not obligatory. Vaccines were offered free of charge to all HCWs. We conducted a comparative descriptive study to investigate the factors that facilitate, or inhibit vaccine uptake among physicians and nurses of a tertiary care university hospital in Ankara, Turkey. The study was conducted at a 2000-bed tertiary-care hospital of Ankara University with an HCW population of 1,234 physicians, 1125 nurses, 385 nurse-assistants, and 549 medical technicians. Health care is mainly provided by nurses and physicians, the main HCW groups who are in close contact (less than one meter) with patients in our institution. Other HCWs are employed by various sub-contracting companies, and they have no reliable records of their vaccination status. Therefore, only physicians and nurses were included in the study. From the beginning of the pandemic, the infection control committee of the hospital organized 11 informative meetings in order to brief every HCW regarding the course of the pandemic and control measures, including vaccination. All the meetings were interactive and many questions on safety of pandemic vaccines were answered by an infectious diseases professor. A total of 1400 HCWs attended these meetings. Vaccination of HCWs was organized by the infection control committee in 2 separate rooms, open between 9:00 am and 4:00 pm everyday on weekdays. The vaccination campaign at the hospital was terminated in February 1, 2010. After the termination of the vaccination campaign, a questionnaire consisting of 22 items grouped in 6 sections (demographics, seasonal influenza vaccine uptake, reasons for accepting or refusing the pandemic vaccine, the source of knowledge on pandemic vaccines, self reported assessment of reliability of these sources, and preventive measures) was prepared. With a given overall vaccination coverage of 20%, assuming a confidence interval (CI) of 95%, and a maximum error of 5%, the sample size was calculated to be at least 236 HCWs. Considering the nonresponders, we randomly selected 300 HCWs from the list of vaccinated HCWs. We then randomly selected 300 HCWs who did not receive pandemic vaccine from the list of hospital employees obtained from the Department of Human Resources. The questionnaires were applied to both HCW groups by the medical students who had been trained in interviewing. Interviews began on March 1, 2010, and data collection was stopped on May 12, 2010 when we reached 236 HCWs in each groups. Refusals to participation were 9.3% in the vaccinated, and 10.8% in the unvaccinated groups. Before answering the questionnaire, all HCWs were informed of the aim of the study, and informed consents were obtained. The study was approved by the institutional research board of the hospital. Chi-square test was used for categorical, and Student’s t-test was used for continuous variables. Bivariate analysis was carried out to evaluate the effect of each independent variable on pandemic influenza vaccine uptake. Multivariate logistic regression analysis was used in determining independent predictors for refusal of the pandemic influenza vaccine. Only significant variables were put into multivariate analysis. A p<0.05 was considered statistically significant. A total of 472 HCWs (236 vaccinated, and 236 unvaccinated) were included in the study. Of the 472 HCWs, 333 (70.5%) were female, 253 (53.6%) were physicians, and 149 (32.6%) were working in the surgical wards. Demographic characteristics of surveyed HCWs and vaccination rates for pandemic influenza according to different variables are summarized in Table 1. By using a multivariate logistic regression modelling 4 variables were found to be independently associated with the pandemic influenza vaccine uptake: being a nurse in a surgical department (OR:0.19; 95% CI:0.08-0.45; p<0.001); using internet as the main source of information (OR:0.31; 95% CI:0.13-0.74; p=0.009); receiving seasonal influenza vaccine in the previous year (OR:2.59; 95% CI:1.13-5.95; p=0.024); and being informed by the meetings held at the hospital (OR:4.54; 95% CI:1.14-17.9; p=0.031).