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Occupational health impact of the 2009 H1N1 flu pandemic: surveillance of sickness absence
  1. Isabel Torá-Rocamora1,
  2. George L Delclos1,2,3,
  3. José Miguel Martínez1,2,
  4. Josefina Jardí4,
  5. Constança Alberti4,
  6. Rafael Manzanera4,
  7. Yutaka Yasui5,
  8. Ramón Clèries6,7,
  9. Aurelio Tobías8,
  10. Fernando G Benavides1,2
  1. 1Department of Experimental and Health Sciences, Center for Research in Occupational Health (CiSAL), Pompeu Fabra University, Barcelona, Spain
  2. 2CIBER in Epidemiology and Public Health, Barcelona, Spain
  3. 3Southwest Center for Occupational and Environmental Health, The University of Texas School of Public Health, Houston, Texas, USA
  4. 4Institut Català d'Avaluacions Mèdiques, Departament de Salut, Generalitat de Catalunya, Barcelona, Spain
  5. 5Department of Public Health Sciences, School of Public Health, University of Alberta, Edmonton, Alberta, Canada
  6. 6Cancer Registry of Catalonia, Catalan Government Cancer Plan-IDIBELL, Hospitalet de Llobregat, Barcelona, Spain
  7. 7Department of Clinical Sciences, University of Barcelona, Barcelona, Spain
  8. 8Instituto de Diagnóstico Ambiental y Estudios del Agua (IDAEA), Consejo Superior de Investigaciones Científicas (CSIC), Barcelona, Spain
  1. Correspondence to George L Delclos, Center for Research in Occupational Health (CiSAL), Universitat Pompeu Fabra, C/Doctor Aiguader 88—Primera planta, Barcelona 08003, Spain; george.delclos{at}


Objectives Workplace absences due to illness can disrupt usual operations and increase costs for businesses. This study of sickness absence due to influenza and influenza-related illness presents a unique opportunity to characterise and measure the impact of the 2009 (H1N1) pandemic, by comparing trends during the pandemic to those of previous years, and adding this information to that obtained by traditional epidemiological surveillance systems.

Methods We compared the numbers of cases of sickness absence due to illness caused by influenza and influenza-related illness in 2007–2009, and in the first 3 months of 2010 in Catalonia (n=811 940) using a time series approach. Trends were examined by economic activity, age and gender. The weekly endemic-epidemic index (EEI) was calculated and its 95% CI obtained with the delta method, with observed and expected cases considered as independent random variables.

Results Influenza activity peaked earlier in 2009 and yielded more cases than in previous years. Week 46 (in November 2009) had the highest number of new cases resulting in sickness absence (EEI 20.99; 95% CI 9.44 to 46.69). Women and the ‘education, health and other social activities’ sector were the most affected.

Conclusions Results indicate that the new H1N1 pandemic had a significant impact on business, with shifts in the timing of peak incidence, a doubling in the number of cases, and changes in the distribution of cases by economic activity sector and gender. Traditional epidemiological surveillance systems could benefit from the addition of information based on sickness absence data.

  • Influenza A (H1N1)
  • occupational health
  • sickness absence
  • occupational health practice
  • investigation of outbreaks of illness

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  • Funding This study was partially funded by grants from the Fondo de Investigación Sanitaria (PT007), the Canadian Institutes for Health Research and the Institut Català d'Avaluacions Mèdiques.

  • Competing interests None.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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