For this calculation, an HCW was considered vaccinated when the onset of symptoms started later than 1 week after the vaccination. The ethical integrity of the study was confirmed by the pH1N1 task force (General

Directorate of Health 2009) and HCWs gave their informed consent to an anonymous analysis of their data. Results The study sample comprises 5,592 HCWs with and without regular patient contact (Fig. 1). In total, 1,720 HCWs were vaccinated against pH1N1 (30.8%), including 52 pregnant HCWs (Table 1). 50.4% of the study population received seasonal TIV for the season 2009/2010. Nurses had the highest vaccination rate (62.5%) for seasonal TIV but only the second highest rate (30.3% compared to 43.9% in physicians) for pH1N1 vaccination (Table 2). Fig. 1 Flow chart of the study population. Pearson’s Chi-square test GDC0449 for pH1N1 infection yes or no depending on pH1N1 vaccination in the group with seasonal TIV (p < 0.0001) and without seasonal TIV (p = 0.004) Table 1 Description of the study population (n = 5,592)   N % Female 4,042 72.3 Age  ≤30 years 1,471 26.3  31–40 years 1,724 30.8  41–50 years 1,236 22.1  >50 years 1,161 20.8 Pregnancy 52 0.9 Profession  Nurses 1,982 35.4  Physicians 1,393 24.9  Auxiliary staff 1,273 22.8  Administration or others 944

16.9 Vaccination  pH1N1 1,720 30.8  Seasonal 09/10 TIV 2,819 50.4  Seasonal CX-5461 price 08/09 TIV 2,127 Protein kinase N1 38.0 Seasonal influenza  No vaccination 2,172 38.8  TIV in 2008/2009 601 10.7  TIV in 2009/2010 1,293 23.1  TIV in both seasons 1,526 27.3 Influenza-like symptoms (ILS) 245 4.4 Confirmed pH1N1 infection 97 1.7 Table 2 Seasonal TIV and 2009 pH1N1 vaccination rates by profession

Profession TIV pH1N1-vacc. N % N % Nurses 1,238 62.5 601 30.3 Physicians 650 46.7 611 43.9 Auxiliary staff 602 47.3 252 19.8 Administration or others 329 34.9 256 27.1 After pH1N1 vaccination, one woman experienced an anaphylactic reaction with dizziness and hypotension lasting a few minutes. No HSP inhibitor review further complications were observed during the first hour after vaccination and no side effects warranting medical attention were reported. After pH1N1 vaccination, myalgia (6.9%), mild local reaction (38.0%) and strong local reaction (1.9%) were reported to the vaccination desk (Table 3). No complications occurred in the 52 pregnant participants. Assessed retrospectively, 83.4% reported no side effects from the seasonal TIV, 12.3% mild local reactions and 2.9% myalgia. Strong local reactions (0.7%), fatigue (0.3%), fever (0.3%), headaches (0.1%) and lymph node swelling (0.1%) were seldom. Therefore, more side effects were reported after pH1N1 vaccination than after the 2009/2010 seasonal TIV.