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Eurosurveillance, Volume 21, Issue 42, 20 October 2016
Systematic Review
Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies
D Mertz 1 2 3 4 , SA Fadel 5 , P Lam 6 , D Tran 7 , JA Srigley 1 8 , SA Asner 7 9 10 , M Science 7 , SP Kuster 11 , J Nemeth 11 , J Johnstone 6 13 14 15 , JR Ortiz 16 , M Loeb 2 3 4
+ Author affiliations
1. Department of Medicine, McMaster University, Hamilton, Canada
2. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada
3. Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
4. Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Canada
5. Centre for Global Health Research, Li Ka Shing Knowledge Institute, St. Michael?s Hospital, Toronto, Canada
6. Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
7. Division of Infectious Diseases, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Canada
8. Department of Laboratory Medicine, BC Children?s & Women?s Hospital, Vancouver, Canada
9. Pediatric Infectious Diseases Unit, Department of Pediatrics, University Hospital Lausanne, Lausanne, Switzerland
10. Infectious Diseases Service, Department of Medicine, University Hospital Lausanne, Lausanne, Switzerland
11. Division of Infectious Diseases and Hospital Epidemiology, University Hospital and University of Zurich, Zurich, Switzerland
13. Public Health Ontario, Infection Prevention and Control, Toronto, Canada
14. St. Joseph?s Health Centre, Toronto, Canada
15. Department of Medicine, University of Toronto, Toronto, Canada
16. Initiative for Vaccine Research, World Health Organization, Geneva, Switzerland
Correspondence: Mark Loeb (loebm@mcmaster.ca)
Citation style for this article: Mertz D, Fadel SA, Lam P, Tran D, Srigley JA, Asner SA, Science M, Kuster SP, Nemeth J, Johnstone J, Ortiz JR, Loeb M. Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies. Euro Surveill. 2016;21(42):pii=30378. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.42.30378
Received:21 October 2015; Accepted:23 April 2016
Influenza vaccination programmes are assumed to have a herd effect and protect contacts of vaccinated persons from influenza virus infection. We searched MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Global Health and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to March 2014 for studies assessing the protective effect of influenza vaccination vs no vaccination on influenza virus infections in contacts. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Of 43,082 screened articles, nine randomised controlled trials (RCTs) and four observational studies were eligible. Among the RCTs, no statistically significant herd effect on the occurrence of influenza in contacts could be found (OR: 0.62; 95% CI: 0.34?1.12). The one RCT conducted in a community setting, however, showed a significant effect (OR: 0.39; 95% CI: 0.26?0.57), as did the observational studies (OR: 0.57; 95% CI: 0.43?0.77). We found only a few studies that quantified the herd effect of vaccination, all studies except one were conducted in children, and the overall evidence was graded as low. The evidence is too limited to conclude in what setting(s) a herd effect may or may not be achieved.
full article
Systematic Review
Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies
D Mertz 1 2 3 4 , SA Fadel 5 , P Lam 6 , D Tran 7 , JA Srigley 1 8 , SA Asner 7 9 10 , M Science 7 , SP Kuster 11 , J Nemeth 11 , J Johnstone 6 13 14 15 , JR Ortiz 16 , M Loeb 2 3 4
+ Author affiliations
1. Department of Medicine, McMaster University, Hamilton, Canada
2. Department of Clinical Epidemiology and Biostatistics, McMaster University, Hamilton, Canada
3. Department of Pathology and Molecular Medicine, McMaster University, Hamilton, Canada
4. Michael G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Canada
5. Centre for Global Health Research, Li Ka Shing Knowledge Institute, St. Michael?s Hospital, Toronto, Canada
6. Dalla Lana School of Public Health, University of Toronto, Toronto, Canada
7. Division of Infectious Diseases, Department of Paediatrics, The Hospital for Sick Children, University of Toronto, Toronto, Canada
8. Department of Laboratory Medicine, BC Children?s & Women?s Hospital, Vancouver, Canada
9. Pediatric Infectious Diseases Unit, Department of Pediatrics, University Hospital Lausanne, Lausanne, Switzerland
10. Infectious Diseases Service, Department of Medicine, University Hospital Lausanne, Lausanne, Switzerland
11. Division of Infectious Diseases and Hospital Epidemiology, University Hospital and University of Zurich, Zurich, Switzerland
13. Public Health Ontario, Infection Prevention and Control, Toronto, Canada
14. St. Joseph?s Health Centre, Toronto, Canada
15. Department of Medicine, University of Toronto, Toronto, Canada
16. Initiative for Vaccine Research, World Health Organization, Geneva, Switzerland
Correspondence: Mark Loeb (loebm@mcmaster.ca)
Citation style for this article: Mertz D, Fadel SA, Lam P, Tran D, Srigley JA, Asner SA, Science M, Kuster SP, Nemeth J, Johnstone J, Ortiz JR, Loeb M. Herd effect from influenza vaccination in non-healthcare settings: a systematic review of randomised controlled trials and observational studies. Euro Surveill. 2016;21(42):pii=30378. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.42.30378
Received:21 October 2015; Accepted:23 April 2016
Influenza vaccination programmes are assumed to have a herd effect and protect contacts of vaccinated persons from influenza virus infection. We searched MEDLINE, EMBASE, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Global Health and the Cochrane Central Register of Controlled Trials (CENTRAL) from inception to March 2014 for studies assessing the protective effect of influenza vaccination vs no vaccination on influenza virus infections in contacts. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) using a random-effects model. Of 43,082 screened articles, nine randomised controlled trials (RCTs) and four observational studies were eligible. Among the RCTs, no statistically significant herd effect on the occurrence of influenza in contacts could be found (OR: 0.62; 95% CI: 0.34?1.12). The one RCT conducted in a community setting, however, showed a significant effect (OR: 0.39; 95% CI: 0.26?0.57), as did the observational studies (OR: 0.57; 95% CI: 0.43?0.77). We found only a few studies that quantified the herd effect of vaccination, all studies except one were conducted in children, and the overall evidence was graded as low. The evidence is too limited to conclude in what setting(s) a herd effect may or may not be achieved.
full article