Influenza vaccine effectiveness in general practice and in hospital patients in Victoria, 2011–2013

Heath A Kelly, Courtney Lane and Allen C Cheng
Med J Aust 2016; 204 (2): 76. || doi: 10.5694/mja15.01017


Objective: To compare influenza vaccine effectiveness in the general practice and hospital settings.

Design: Analysis of annual case test-negative studies.

Setting: Victorian sentinel hospitals and general practices, 2011–2013.

Participants: Patients presenting to general practitioners, or those admitted to hospital with an influenza-like illness who were tested for influenza using a polymerase chain reaction assay. Cases were patients with a positive test result for influenza; non-cases (controls) had a negative test result.

Main outcome measures: Vaccine effectiveness against laboratory-confirmed influenza.

Results: Hospitalised patients were on average older and reported a higher proportion of comorbidities than general practice patients. The pooled estimate of influenza vaccine effectiveness against laboratory-confirmed infection for the 3 years was 50% (95% CI, 26%–66%) for general practice patients and 39% (95% CI, 28%–47%) for patients admitted to hospital.

Conclusions: Influenza vaccines appeared to be similarly modestly effective in the general practice and hospital settings. Influenza vaccination appears to prevent hospital admission by preventing symptomatic infection rather than by attenuating the severity of illness.

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  • Heath A Kelly1
  • Courtney Lane2
  • Allen C Cheng3,4

  • 1 Victorian Infectious Diseases Reference Laboratory, Melbourne, VIC
  • 2 University of Melbourne, Melbourne, VIC
  • 3 Alfred Health, Melbourne, VIC
  • 4 Monash University, Melbourne, VIC



We gratefully acknowledge the contributions to the two surveillance schemes of the following people: Tom Kotsimbos, Paul Kelly, Deborah Friedman, Tony Korman and Louis Irving (FluCAN investigators); Kylie Carville and James Fielding (VicSPIN investigators) and Kristina Grant (VicSPIN data manager). We thank all hospital staff and general practices participating in the two surveillance schemes. FluCAN is funded by the Australian Department of Health. VicSPIN is supported by the Victorian Government Department of Health. Allen Cheng is supported by an NHMRC Career Development Fellowship.

Competing interests:

No relevant disclosures.

  • 1. Australian Government. Department of Health and Ageing; National Health and Medical Research Council. The Australian immunisation handbook, 9th edition. Canberra: Australian Government, 2008. (accessed Nov 2015).
  • 2. Australian Government. Department of Health; National Health and Medical Research Council. The Australian immunisation handbook 10th edition (updated June 2015). (accessed Nov 2015).
  • 3. Kelly H, Carville K, Grant K, et al. Estimating influenza vaccine effectiveness from routine surveillance data. PLoS One 2009; 4: e5079.
  • 4. Cheng A, Tosombis J, Kelly H, 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: 7320-7325.
  • 5. Fielding J, Grant K, Tran T, Kelly H. Moderate influenza vaccine effectiveness in Victoria, Australia 2011. Euro Surveill 2012; 7: pii=20115.
  • 6. Sullivan S, Komadenis N, Grant K, et al. Influenza vaccine effectiveness in the Victorian influenza season of 2012: influences of waning immunity and vaccine match. J Med Virol 2014; 86: 1017-1025.
  • 7. Carville K, Grant K, Sullivan SG, et al. Understanding protection from influenza vaccine in the community: the Victorian influenza season, 2013. Vaccine 2015; 33: 341-345.
  • 8. Cheng AC, Holmes M, Irving LB, et al. Influenza vaccine effectiveness against hospitalisation with confirmed influenza in the 2010–11 seasons: a test-negative observational study. PLoS One 2013; 8: e68760.
  • 9. Cheng AC, Brown S, Waterer G, et al. Influenza epidemiology, vaccine coverage and vaccine effectiveness in sentinel Australian hospitals in 2012: the Influenza Complications Alert Network (FluCAN). Commun Dis Intell Q Rep 2013; 37: E246-E252.
  • 10. Cheng AC, Dwyer DE, Holmes M, et al. Influenza epidemiology, vaccine coverage and vaccine effectiveness in sentinel Australian hospitals in 2013: the Influenza Complications Alert Network. Commun Dis Intell Q Rep 2014; 38: E143-E149.
  • 11. Foppa IM, Haber M, Ferdinands J, Shay DK. The case test-negative design for studies of the effectiveness of seasonal influenza vaccine. Vaccine 2013; 31: 3104-3109.
  • 12. Suess T, Remschmidt C, Schink S, et al. Comparison of shedding characteristics of seasonal influenza virus (sub)types and influenza A(H1N1)pdm09; Germany, 2007–2011. PLoS One 2012; 7: e51653.
  • 13. Tay EL, Grant K, Kirk M, et al. Exploring a proposed WHO method for defining thresholds for influenza surveillance. PLoS One 2013; 8: e77244.
  • 14. Darvishian M, Bijlsma MJ, Hak E, van den Heuvel ER. Effectiveness of seasonal influenza vaccine in community dwelling elderly people: a meta-analysis of test-negative design case-control studies. Lancet Infect Dis 2014; 14: 1228-1239.
  • 15. Petrie JG, Ohmit SE, Johnson E, et al. Efficacy studies of influenza vaccines: effect of end points used and characteristics of vaccine failures. J infect Dis 2011; 203: 1309-1315.
  • 16. Jackson LA, Nelson JC, Benson P, et al. Functional status is a confounder of the association of influenza vaccine and risk of all-cause mortality in seniors. Int J Epidemiol 2006; 35: 345-352.
  • 17. Goodwin K, Viboud C, Simonsen L. Antibody response to influenza vaccination in the elderly: a quantitative review. Vaccine 2006; 24: 1159-1169.
  • 18. McLean HQ, Thompson MG, Sundaram ME, et al. Influenza vaccine effectiveness in the United States during 2012–13: variable protection by age and virus type. J Infect Dis 2015; 211: 1529-1240.
  • 19. Turner N, Pierse N, Bisselo A, et al. The effectiveness of seasonal trivalent inactivated influenza vaccine in preventing laboratory confirmed influenza hospitalisations in Auckland, New Zealand in 2012. Vaccine 2014; 32: 3687-3693.
  • 20. Kelly H, Sullivan S, Grant K, Fielding J. Moderate influenza vaccine effectiveness with variable effectiveness by match between circulating and vaccine strains in Australian adults aged 20–64 years, 2007–11. Influenza Resp Vir 2013; 7: 729-737.
  • 21. Osterholm MT, Kelley NS, Sommer A, Belongia EA. Efficacy and effectiveness of influenza vaccines: a systematic review and meta-analysis. Lancet 2012; 12: 36-44.
  • 22. Tricco AC, Chit A, Soobiah C, et al. Comparing influenza vaccine efficacy against mismatched and matched strains: a systematic review and meta-analysis. BMC Medicine 2013, 11: 153.
  • 23. Castilla J, Godoy P, Domínguez A, et al. Influenza vaccine effectiveness in preventing outpatient, inpatient, and severe cases of laboratory-confirmed influenza. Clin Inf Dis 2013; 57: 167-175.
  • 24. Turner N, Pierse N, Huang QS, et al. Interim estimates of the effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand, in 2014. Euro Surveill 2014; 19: pii=20934.


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access_time 10:41, 10 February 2016
Mark Jones

I have two comments/queries:
1. Was assessment of vaccination status performed blinded to case-control status?

2. Unfortunately this study design carries little clinical relevance, telling us very little about effectiveness in terms of preventing severe outcomes, absolute risk reduction and NNT. It really only tells us the odds of producing a negative PCR test with and without a record of vaccination. The discussion provides a hint of true efficacy where the authors discuss the need to carry out a randomised controlled trial with tens of thousands of participants to enable sufficient statistical power. This suggests the effect of vaccine is very small.

Competing Interests: No relevant disclosures

Dr Mark Jones
University of Queensland

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