A total of 807 HCWs were interviewed before the first day of the vaccination programme. The departments with highest numbers of participants were internal medicine (19.1%, n = 151), general surgery (9.3%, n = 74) and anaesthesia & reanimation (5.2%, n = 41).
Among participants, 363 were doctors (45.3%), 293 were nurses (36.6%), followed by 111 health technicians (13.9%) and 34 others (4.2%), with a female predominance (66.5%, n = 536). Mean age of participants was 35.1 ± 8.8 (range 19 - 66, median 34). Mean duration of work in years was 12.1 ± 9.0 (range 1 - 44, median 10).
Regarding pandemic H1N1 vaccination attitude, only 143 (17.7%) were willing to get vaccinated. Among HCWs, 496 (60.6%) had children aged 6 months to 24 years and only 53 (11.1%) were willing to vaccinate them. Among participants, 634 (78.9%) perceived themselves under risk of influenza, 153 (19.0%) were vaccinated against seasonal influenza in the 2008-2009 season and 305 (37.9%) were in the last five years. The responses of HCWs to these questions are shown in detail in Table .
HCW's risk perception, previous seasonal influenza vaccination practices and attitudes toward vaccination against H1N1
The most common underlying reason for unwillingness or hesitation concerning pandemic H1N1 vaccination was possible side effects, followed by the lack of comprehensive field evaluation before marketing. The distribution and variety of reasons underlying hesitation and unwillingness are shown in Table . Indecisive participants were more likely to be concerned about possible side effects while participants rejecting the vaccine more likely thought that the disease was mild or that contracting the disease was safer (p < 0.05).
Reasons underlying unwillingness or hesitation to be vaccinated against pandemic H1N1 (n, %)
Mean age of indecisive HCWs was significantly lower than participants rejecting the vaccine. Females, nurses, and HCWs working in the surgical departments were more likely to reject vaccination (p < 0.05). To explore possible effect modification by profession, a stratified analysis was done. Among female participants, only 20 (7.0%) of nurses were willing to be vaccinated vs. 51 (20.6%) among females with other professions (χ2 = 21.211, p < 0.001). Doctors, HCWs working in internal departments and HCWs that were previously vaccinated against seasonal influenza were more likely to accept vaccination (p < 0.05). Health technicians and other professions did not have a significantly different attitude than others (Table ). A similar pattern was observed for attitudes toward vaccinating their children, except for the disappearing effect of gender.
Factors influencing attitudes toward getting vaccinated against pandemic influenza
Among individual departments with >10 participants, the three clinics with highest intent for vaccination were respiratory diseases (42.9%, n = 15 of 35), infectious diseases (40.0%, 6 of 15) and cardiovascular surgery (35.7%, 5 of 14), respectively. The highest rates of opposition were observed in plastic and reconstructive surgery (75.0%, n = 12 of 16), otorhinolaringology (64.3%, 9 of 14) and general surgery (60.8%, 45 of 74) clinics.
Pandemic H1N1 vaccines were administered to volunteering health HCWs during the week following the interviews, along with the simultaneous administration of seasonal influenza vaccine. Vaccination status could be tracked among 92.8% (n = 749) of participants, who had provided their full names on the questionnaires. Of these, 228 (30.4%) were vaccinated against H1N1 and 521 (69.6%) were not. The distribution of their actual vaccination status according to their intention in the previous week and their seasonal influenza vaccination status for the previous year is presented in Table .
Actual vaccination status of HCWs according to their intention and past seasonal influenza vaccination (n, %)
When risk perception was analyzed according to age categories, a significant difference was noted. The perceived risk decreased with age: 81.8%, 82.5%, 75.7% and 59.3% for the age categories <30, 30-39, 40-49 and ≥50, respectively (χ2 = 18.270, p < 0.001, n = 225, 222, 137, 35, respectively). Such a trend was not observed for actual vaccination rates, but vaccination rate was significantly lower for HCWs ≥50 years old. The effects of possible factors that could influence vaccination status are shown in Table along with factors that could have an impact on risk perception.
Factors influencing perceived risk of influenza and final H1N1 vaccination status
Though HCWs who perceived themselves under risk of pandemic H1N1 were significantly younger (mean ages 34.4 ± 8.3 and 37.5 ± 9.9, respectively, t = -3.754, p = < 0.001), there was no significant difference in mean ages of vaccinated and unvaccinated HCWs (34.5 ± 8.2 and 35.2 ± 9.1 years, respectively, t = -0.941, p = 0.347). Likewise, HCWs who felt under risk had a shorter duration of employment (11.5 ± 8.7 vs. 14.0 ± 10.1 years, t = -2.831, p = 0.005) while there was no significant difference in mean duration of employment among vaccinated and unvaccinated HCWs (11.2 ± 8.6 vs. 12.3 ± 9.3 years, t = -0.1486, p = 0.138). There was no significant difference in the past seasonal influenza vaccination rates among different professions and departments (chi-square p > 0.05).
Among departments with >10 participants, actual vaccination rates were the highest in infectious diseases (76.9%, n = 10 of 13), respiratory diseases (70.6%, 24 of 34) and campus outpatient clinics (57.1%, 8 of 14) and the lowest in otorhinolaringology (0.0%, 0 of 14), plastic and reconstructive surgery (0.0%, 0 of 13), general surgery clinics (4.5%, 3 of 66).
According to the multivariate logistic regression analysis including the variables in Table , HCWs aged <50 years, HCWs perceiving a higher risk of pandemic H1N1 and HCWs vaccinated against seasonal influenza in the 2008-09 season were significantly more likely to get vaccinated. However, not being a doctor but a nurse or a health technician and working in a surgical department were significant variables associated with non-vaccination. Odds ratios and 95% confidence intervals are presented in Table .
Multivariate logistic regression analysis on determinants of H1N1 vaccination status