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Estimating vaccine effectiveness against severe influenza in England and Scotland 2011/2012: applying the screening method to data from intensive care surveillance systems

  • H. L. THOMAS (a1) (a2) (a3), N. ANDREWS (a1), H. K. GREEN (a1), N. L. BODDINGTON (a1), H. ZHAO (a1), A. REYNOLDS (a4), J. McMENAMIN (a4) and R. G. PEBODY (a1)...

Methods for estimating vaccine effectiveness (VE) against severe influenza are not well established. We used the screening method to estimate VE against influenza resulting in intensive care unit (ICU) admission in England and Scotland in 2011/2012. We extracted data on confirmed influenza ICU cases from severe influenza surveillance systems, and obtained their 2011/2012 trivalent influenza vaccine (TIV) status from primary care. We compared case vaccine uptake with population vaccine uptake obtained from routine monitoring systems, adjusting for age group, specific risk group, region and week. Of 60 influenza ICU cases reported, vaccination status was available for 56 (93%). Adjusted VE against ICU admission for those aged ⩾65 years was −10% [95% confidence interval (CI) −207 to 60], consistent with evidence of poor protection from the 2011/2012 TIV in 2011/2012. Adjusted VE for those aged <65 years in risk groups was −296% (95% CI −930 to −52), suggesting significant residual confounding using the screening method in those subject to selective vaccination.

Corresponding author
* Author for correspondence: Dr H. L. Thomas, Health Protection Agency, Health Protection Services Colindale, 61 Colindale Avenue, London NW9 5EQ, UK. (Email:
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1. World Health Organization. Recommended composition of influenza virus vaccines for use in the 2012–2013 northern hemisphere influenza season, February 2012 ( Accessed 12 August 2012.
2. Department of Health. Immunisation against Infectious Disease, 2006. Chapter 19. Influenza, updated 3 November 2011 ( Accessed 12 July 2012.
3. Kissling E, Valenciano M. I-MOVE case-control studies team. Early estimates of seasonal influenza vaccine effectiveness in Europe, 2010/11: I-MOVE, a multicentre case-control study. Eurosurveillance 2012; 17: pii=20146.
4. Valenciano M, et al. Sudy designs for timely estimation of influenza vaccine effectiveness using European sentinel practitioner networks. Vaccine 2010; 28: 73817388.
5. Pebody RG, et al. Age-specific vaccine effectiveness of seasonal 2010/2011 and pandemic influenza A(H1N1) 2009 vaccines in preventing influenza in the United Kingdom. Epidemiology and Infection 2012; 13: 111.
6. Hardelid P, et al. Effectiveness of trivalent and pandemic influenza vaccines in England and Wales 2008–2010: results from a cohort study in general practice. Vaccine 2012; 30: 13711378.
7. Hellenbrand W, et al. Prospective hospital-based case-control study to assess the effectiveness of pandemic influenza A(H1N1)pdm09 vaccination and risk factors for hospitalization in 2009–2010 using matched hospital and test-negative controls. BMC Infectious Diseases 2012; 12: 127.
8. Talbot HK, et al. Effectiveness of seasonal vaccine in preventing confirmed influenza-associated hospitalizations in community dwelling older adults. Journal of Infectious Diseases 2011; 203: 500508.
9. Cheng AC, et al. Effectiveness of H1N1/09 monovalent and trivalent influenza vaccines against hospitalization with laboratory-confirmed H1N1/09 influenza in Australia: a test-negative case control study. Vaccine 2011; 29: 73207325.
10. Puig-Barberà J, et al. Effectiveness of the 2010–2011 seasonal influenza vaccine in preventing confirmed influenza hospitalizations in adults: a case-case comparison, case-control study. Vaccine 2012; 30: 57145720.
11. Bolotin S, et al. A new sentinel surveillance system for severe influenza in England shows a shift in age distribution of hospitalised cases in the post-pandemic period. PLoS One 2012; 7: e30279.
12. Gates P, et al. Collection of routine national seasonal influenza vaccine coverage data from GP practices in England using a web-based collection system. Vaccine 2009; 27: 66696677.
13. Farrington CP. Estimation of vaccine effectiveness using the screening method. International Journal of Epidemiology 1993; 22: 742746.
14. Health Protection Agency. Surveillance of influenza and other respiratory viruses in the UK: 2010–2011 report ( Accessed 10 September 2012.
15. Pebody RG, et al. Vaccine effectiveness of 2011/12 trivalent seasonal influenza vaccine in preventing laboratory-confirmed influenza in primary care in the United Kingdom: evidence of waning intra-seasonal protection. Eurosurveillance 2013; 18: pii=20389.
16. Kissling E, Valenciano M. iMOVE case-control studies team. Early estimates of seasonal influenza vaccine effectiveness in target groups for vaccination: results from the iMOVE multicentre case-control study, 2011–12. Eurosurveillance 2012; 17: pii=20146.
17. Hak E, et al. Confounding by indication in non-experimental evaluation of vaccine effectiveness: the example of prevention of influenza complications. Journal of Epidemiology and Community Health 2002; 56: 951955.
18. Legrand J, Vergu E, Flahault A. Real-time monitoring of the influenza vaccine field effectiveness. Vaccine 2006; 24: 66056611.
19. Chen RT, Orenstein WA. Epidemiologic methods in immunization programmes. Epidemiologic Reviews 1996; 18: 99117.
20. Mary-Krause M, Mary J-Y, Valleron A-J. Conditions of validation and use of the screening method for vaccine efficacy evaluation. Revue d'Epidemiologie et de Sante Publique 1993; 41: 155160.
21. Joint Committee on Vaccination and Immunisation Statement the Annual Influenza Vaccination Programme. 16 November 2011 ( Accessed 10 September 2012.
22. Foster DA, et al. Influenza vaccine effectiveness in preventing hospitalisation for pneumonia in the elderly. American Journal of Epidemiology 1992; 136: 296307.
23. Legrand J, Vergu E, Flahault A. Real-time monitoring of the influenza vaccine field effectiveness. Vaccine 2006; 24: 4446.
24. Bonmarin I, et al. First estimates of influenza vaccine effectiveness among severe influenza cases, France, 2011/12. Eurosurveillance 2012; 17: pii=20163.
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Epidemiology & Infection
  • ISSN: 0950-2688
  • EISSN: 1469-4409
  • URL: /core/journals/epidemiology-and-infection
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