ReviewEffectiveness of influenza vaccines in preventing severe influenza illness among adults: A systematic review and meta-analysis of test-negative design case-control studies
Section snippets
Background
Each year, seasonal influenza epidemics affect 20–30% of children and 5–10% of adults globally1 and that they cause three to five million severe (hospitalized) cases and 250,000 to 500,000 deaths worldwide.2 Pulmonary complications, as a direct consequence of influenza infection, after secondary bacterial infection or through the exacerbation of chronic conditions,3 and neuromuscular or cardiac complications4 may cause severe forms of influenza. Consequently, individuals at risk of developing
Methods
We conducted a systematic review and meta-analysis of extracted IVE estimates.
Results
We identified 3411 unduplicated publications, of which we selected 407 for abstract review and further selected 93 for full-text review. We extracted data from 50 articles and included 30 of them in our IVE meta-analysis21, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60 (Fig. 1, Table S1, Table S2). Nineteen studies were conducted in the Northern hemisphere and included studies covering seasons 2009–10 through 2015–16 (Table 1
Discussion
Our meta-analysis estimated at 41% (95%CI: 34;48) the overall seasonal IVE against hospitalizations associated with laboratory confirmed influenza virus infections among adults, with (sub)type IVE of 48% (95%CI :37;59) against influenza A(H1N1)pdm09, 37% (95%CI: 24;50) against influenza A(H3N2) and 38% (95%CI: 23;53) against influenza B viruses. Monovalent pandemic vaccine yielded to the highest pooled IVE at 72% (95%CI: 22;100). Our results suggested that IVE was significantly higher among
Conclusion
In conclusion, our review of the published literature suggests that among vaccinated individuals influenza vaccines may prevent nearly half of the laboratory confirmed hospitalizations associated with influenza viruses. We observed lower IVE among persons 65 years and older compared to adults aged 18–64 years. We also noted poor performance of the seasonal influenza vaccines against influenza A(H3N2) viruses among the elderly in seasons characterized by a mismatch between vaccine and
Contributors
MR and NEO designed the study. MR and NEO screened and abstracted publications. MR and SS analysed data. MR, NEO, and MT interpreted the results. MR wrote the manuscript, with editorial contributions from NEO, AM, AL, MT and SS. All authors reviewed the manuscript for accuracy and scientific content.
Conflict of interest
All authors declare no competing interests.
Acknowledgements
We thank authors of the following included studies for responding to queries and providing additional data: John Treanor, David Shay, Jessie Chung, Brendan Flannery, Jesus Castilla Catalan, Itziar Casado Buesa, Iván Martínez Baz. We would like to thank Marta Valenciano and Esther Kissling for their methodological input.
References (90)
- et al.
Complications of viral influenza
Am J Med
(2008) - et al.
Pathogenesis of influenza virus infections: the good, the bad and the ugly
Curr Opin Virol
(2012) - et al.
Assessing the burden of influenza and other respiratory infections in England and Wales
J Infect
(2007) - et al.
The annual impact of seasonal influenza in the US: measuring disease burden and costs
Vaccine
(2007) - et al.
Effectiveness of seasonal 2008–2009, 2009–2010 and pandemic vaccines, to prevent influenza hospitalizations during the autumn 2009 influenza pandemic wave in Castellón, Spain. A test-negative, hospital-based, case-control study
Vaccine
(2010) - et al.
Study designs for timely estimation of influenza vaccine effectiveness using European sentinel practitioner networks
Vaccine
(2010) - et al.
Variable influenza vaccine effectiveness by subtype: a systematic review and meta-analysis of test-negative design studies
Lancet Infect Dis
(2016) - et al.
Effectiveness of seasonal influenza vaccination in community-dwelling elderly people: an individual participant data meta-analysis of test-negative design case-control studies
Lancet Respir Med
(2017) - et al.
Meta-analysis in clinical trials
Control Clin Trials
(1986) - et al.
The effectiveness of seasonal trivalent inactivated influenza vaccine in preventing laboratory confirmed influenza hospitalisations in Auckland, New Zealand in 2012
Vaccine
(2014)
Influenza vaccine effectiveness in preventing hospitalization among Beijing residents in China, 2013–15
Vaccine
Influenza vaccine effectiveness for hospital and community patients using control groups with and without non-influenza respiratory viruses detected, Auckland, New Zealand 2014
Vaccine
FluCAN Investigators. Influenza vaccine effectiveness against hospitalisation with influenza in adults in Australia in 2014
Vaccine
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
Effectiveness of subunit influenza vaccination in the 2014–2015 season and residual effect of split vaccination in previous seasons
Vaccine
Influenza vaccine effectiveness by test-negative design – Comparison of inpatient and outpatient settings
Vaccine
The confounded effects of age and exposure history in response to influenza vaccination
Vaccine
Influenza vaccination status is not associated with influenza testing among children: implications for observational studies of vaccine effectiveness
Vaccine
Vaccine effectiveness in preventing influenza hospitalizations in Navarre, Spain, 2010–2011: cohort and case-control study
Vaccine
Effects of Repeated Annual Inactivated Influenza Vaccination among Healthcare Personnel on Serum Hemagglutinin Inhibition Antibody Response to A/Perth/16/2009 (H3N2)-like virus during 2010–11
Vaccine
Influenza vaccines. WHO position paper
Wkly Epidemiol Rec
WHO | influenza (seasonal) [Internet]
Pulmonary complications of interpandemic influenza A in hospitalized adults
J Infect Dis
Influenza epidemics and acute respiratory disease activity are associated with a surge in autopsy-confirmed coronary heart disease death: results from 8 years of autopsies in 34,892 subjects
Eur Heart J
Prevention and control of influenza: recommendations of the Advisory Committee on Immunization Practices (ACIP), 2008
MMWR Recomm Rep
Modelling hospital admissions for lower respiratory tract infections in the elderly in England
Epidemiol Infect
Hospitalizations associated with influenza and respiratory syncytial virus in the United States, 1993–2008
Clin Infect Dis
FluView: laboratory-confirmed influenza hospitalizations – preliminary cumulative rates as of May 06, 2017 [Internet]
Seasonal influenza vaccination and antiviral use in Europe Overview of vaccination recommendations and coverage rates in the EU Member States for the 2013–14 and 2014–15 influenza seasons
Influenza vaccination in the Americas: progress and challenges after the 2009 A(H1N1) influenza pandemic
Hum Vaccin Immunother
Prevention and control of influenza pandemics and annual epidemics, Resolution of the 56th World Health Assembly, WHA 56.19, 2003. [Internet]
Influenza vaccination for older people
Subjective and objective risk as predictors of influenza vaccination during the vaccine shortage of 2004–2005
Clin Infect Dis
Vaccine hesitancy: an overview
Hum Vaccin Immunother
FluCAN 2009: initial results from sentinel surveillance for adult influenza and pneumonia in eight Australian hospitals
Med J Aust
Southern Hemisphere Influenza and Vaccine Effectiveness Research and Surveillance
Influenza Other Respir Viruses
Effectiveness of vaccine against medical consultation due to laboratory-confirmed influenza: results from a sentinel physician pilot project in British Columbia, 2004–2005
Can Commun Dis Rep
Case-control designs in the study of common diseases: updates on the demise of the rare disease assumption and the choice of sampling scheme for controls
Int J Epidemiol
Influenza vaccine effectiveness among high-risk groups: a systematic literature review and meta-analysis of case-control and cohort studies
Hum Vaccin Immunother
Quantifying heterogeneity in a meta-analysis
Stat Med
Systematic reviews in health care: investigating and dealing with publication and other biases in meta-analysis
BMJ
Bias in meta-analysis detected by a simple, graphical test
BMJ
Effectiveness of seasonal trivalent inactivated influenza vaccine in preventing influenza hospitalisations and primary care visits in Auckland, New Zealand, in 2013
Euro Surveill
Effectiveness of seasonal influenza vaccines in the United States during a season with circulation of all three vaccine strains
Clin Infect Dis
2011–12 seasonal influenza vaccines effectiveness against confirmed A(H3N2) influenza hospitalisation: pooled analysis from a European network of hospitals. A pilot study
PLoS ONE
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The findings and conclusions in this report are those of the authors and do not necessarily represent the official position of the Centers for Disease Control and Prevention.
Funding: None.