title: High effectiveness of pandemic influenza A (H1N1) vaccination in healthcare workers from a Portuguese hospital.
abstract: OBJECTIVE
  Vaccination of healthcare workers (HCWs) was made a high priority during the phase six pandemic of the novel influenza A H1N1 (pH1N1) virus. We surveyed adherence to pH1N1 vaccination and the incidence of pH1N1 infection between vaccinated and unvaccinated HCWs.
  
  
  METHODS
  Employees at the S. João Hospital in Porto, Portugal, were offered pH1N1 vaccinations free of charge. Pandemrix(®) was the vaccine administered. As part of the pandemic plan, employees with influenza-like symptoms (ILS) were called upon to take an RT-PCR H1N1 test. If the test results were positive, they had to stay off work for at least 7 days. Sociodemographic data, vaccination status, contact with infectious patients, ILS and pH1N1 test results were documented in a standardised manner.
  
  
  RESULTS
  The survey population comprised 5,592 employees. The vaccination rate was 30.8% (n = 1,720) for pH1N1 and 50.4% (n = 2,819) for the 2009/2010 seasonal trivalent inactivated influenza vaccine (TIV). One mild anaphylactic reaction occurred after pH1N1 vaccination. Minor local side effects occurred more often after pH1N1 vaccination than after 2009/2010 seasonal TIV (38.0% vs. 12.3%). Pandemic H1N1 infection was diagnosed in 97 HCWs (1.7%). Compared to employees with no regular patient contact, nurses (2.8%) had the highest risk of pH1N1 infection (adjusted OR 3.8; 95% CI 1.2-6.8). Vaccination reduced the pH1N1 infection risk (OR 0.12; 95% CI 0.05-0.29). Vaccine effectiveness was 90.4% (95% CI 73.5-97.3%).
  
  
  CONCLUSIONS
  Vaccination reduced the pH1N1 infection risk considerably. The pandemic plan to contain the pH1N1 infection was successful. Nurses had the highest risk of pH1N1 infection and are therefore a target group for vaccination measures.
authors: Occupational Health Division, S. João Hospital, EPE, Porto, Portugal.
authors: José Torres
authors: JT
authors: Costa
authors: Rui
authors: R
authors: Silva
authors: Margarida
authors: M
authors: Tavares
authors: Albert
authors: A
authors: Nienhaus
mesh_terms: D000328:Adult; D005260:Female; D006282:Health Personnel; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000235:genetics / Q000276:immunology* / Q000302:isolation & purification; D007252:Influenza Vaccines / Q000008:administration & dosage* / Q000009:adverse effects; D007251:Influenza, Human / Q000453:epidemiology* / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D009313:National Health Programs; D011174:Portugal / Q000453:epidemiology; D012367:RNA, Viral / Q000032:analysis; D014611:Vaccination / Q000706:statistics & numerical data*
chemical_list: D007252:Influenza Vaccines; D012367:RNA, Viral