Meta-Analysis

. 2019 Jan 10;17(1):9.

doi: 10.1186/s12916-018-1239-8.

The impact of repeated vaccination on influenza vaccine effectiveness: a systematic review and meta-analysis

Lauren C Ramsay^{1

2}, Sarah A Buchan^{1

2}, Robert G Stirling^{2

3}, Benjamin J Cowling⁴, Shuo Feng⁴, Jeffrey C Kwong^{1

2

5

6

7}, Bryna F Warshawsky^{8

9}

Affiliations

¹ Public Health Ontario, 480 University Avenue Suite 300, Toronto, Ontario, M5G 1V2, Canada.
² Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
³ Public Health Agency of Canada, 130 Colonnade Road, Ottawa, Ontario, K1A 0K9, Canada.
⁴ WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China.
⁵ Institute for Clinical Evaluative Sciences, Veterans Hill Trail, 2075 Bayview Avenue G1 06, Toronto, Ontario, M4N 3M5, Canada.
⁶ Department of Family & Community Medicine, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
⁷ University Health Network, 399 Bathurst St, Toronto, Ontario, M5T 2S8, Canada.
⁸ Public Health Ontario, 480 University Avenue Suite 300, Toronto, Ontario, M5G 1V2, Canada. bryna.warshawsky@oahpp.ca.
⁹ Department of Epidemiology and Biostatistics, Western University, 1151 Richmond St, London, Ontario, N6A 3K7, Canada. bryna.warshawsky@oahpp.ca.

PMID: 30626399
PMCID: PMC6327561
DOI: 10.1186/s12916-018-1239-8

Meta-Analysis

The impact of repeated vaccination on influenza vaccine effectiveness: a systematic review and meta-analysis

Lauren C Ramsay et al. BMC Med. 2019.

. 2019 Jan 10;17(1):9.

doi: 10.1186/s12916-018-1239-8.

Authors

Lauren C Ramsay^{1

2}, Sarah A Buchan^{1

2}, Robert G Stirling^{2

3}, Benjamin J Cowling⁴, Shuo Feng⁴, Jeffrey C Kwong^{1

2

5

6

7}, Bryna F Warshawsky^{8

9}

Affiliations

¹ Public Health Ontario, 480 University Avenue Suite 300, Toronto, Ontario, M5G 1V2, Canada.
² Dalla Lana School of Public Health, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
³ Public Health Agency of Canada, 130 Colonnade Road, Ottawa, Ontario, K1A 0K9, Canada.
⁴ WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong, China.
⁵ Institute for Clinical Evaluative Sciences, Veterans Hill Trail, 2075 Bayview Avenue G1 06, Toronto, Ontario, M4N 3M5, Canada.
⁶ Department of Family & Community Medicine, University of Toronto, 155 College St, Toronto, Ontario, M5T 3M7, Canada.
⁷ University Health Network, 399 Bathurst St, Toronto, Ontario, M5T 2S8, Canada.
⁸ Public Health Ontario, 480 University Avenue Suite 300, Toronto, Ontario, M5G 1V2, Canada. bryna.warshawsky@oahpp.ca.
⁹ Department of Epidemiology and Biostatistics, Western University, 1151 Richmond St, London, Ontario, N6A 3K7, Canada. bryna.warshawsky@oahpp.ca.

PMID: 30626399
PMCID: PMC6327561
DOI: 10.1186/s12916-018-1239-8

Abstract

Background: Conflicting results regarding the impact of repeated vaccination on influenza vaccine effectiveness (VE) may cause confusion regarding the benefits of receiving the current season's vaccine.

Methods: We systematically searched MEDLINE, Embase, PubMed, and Cumulative Index to Nursing and Allied Health Literature from database inception to August 17, 2016, for observational studies published in English that reported VE against laboratory-confirmed influenza for the following four vaccination groups: current season only, prior season only, both seasons, and neither season. We pooled differences in VE (∆VE) between vaccination groups by influenza season and type/subtype using a random-effects model. The study protocol is registered with PROSPERO (registration number: CRD42016037241).

Results: We identified 3435 unique articles, reviewed the full text of 634, and included 20 for meta-analysis. Compared to prior season vaccination only, vaccination in both seasons was associated with greater protection against influenza H1N1 (∆VE = 25%; 95% CI 14%, 35%) and B (∆VE = 18%; 95% CI 3%, 33%), but not H3N2 (∆VE = 7%; 95% CI - 7%, 21%). Compared to no vaccination for either season, individuals who received the current season's vaccine had greater protection against H1N1 (∆VE = 62%; 95% CI 51%, 70%), H3N2 (∆VE = 45%; 95% CI 35%, 53%), and B (∆VE = 64%; 95% CI 57%, 71%). We observed no differences in VE between vaccination in both seasons and the current season only for H1N1 (∆VE = 3%; 95% CI - 8%, 13%), but less protection against influenza H3N2 (∆VE = - 20%; 95% CI - 36%, - 4%), and B (∆VE = - 11%; 95% CI - 20%, - 2%).

Conclusions: Our results support current season vaccination regardless of prior season vaccination because VE for vaccination in the current season only is higher compared to no vaccination in either season for all types/subtypes, and for H1N1 and influenza B, vaccination in both seasons provides better VE than vaccination in the prior season only. Although VE was lower against H3N2 and B for individuals vaccinated in both seasons compared to those vaccinated in the current season only, it should be noted that past vaccination history cannot be altered and this comparison disregards susceptibility to influenza during the prior season among those vaccinated in the current season only. In addition, our results for H3N2 were particularly influenced by the 2014-2015 influenza season and the impact of repeated vaccination for all types/subtypes may vary from season to season. It is important that future VE studies include vaccination history over multiple seasons to evaluate repeated vaccination in more detail.

Keywords: Influenza; Repeated vaccination; Vaccine effectiveness.

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Conflict of interest statement

Ethics approval and consent to participate

Not applicable

Consent for publication

Not applicable

Competing interests

The authors declare that they have no competing interests.

Publisher’s Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Figures

**Fig. 1**
PRISMA flow diagram of study selection

**Fig. 2**
Comparison of VE estimates against influenza H1N1 in those vaccinated in both seasons versus those vaccinated in the prior season only

**Fig. 3**
Comparison of VE estimates against influenza H3N2 in those vaccinated in both seasons versus those vaccinated in the prior season only

**Fig. 4**
Comparison of VE estimates against influenza B in those vaccinated in both seasons versus those vaccinated in the prior season only

**Fig. 5**
Comparison of VE estimates against influenza H1N1 in those vaccinated in the current season only versus those vaccinated in neither season

**Fig. 6**
Comparison of VE estimates against influenza H3N2 in those vaccinated in the current season only versus those vaccinated in neither season

**Fig. 7**
Comparison of VE estimates against influenza B in those vaccinated in the current season only versus those vaccinated in neither season

**Fig. 8**
Comparison of VE estimates against influenza H1N1 in those vaccinated in both seasons versus those vaccinated in the current season only

**Fig. 9**
Comparison of VE estimates against influenza H3N2 in those vaccinated in both seasons versus those vaccinated in the current season only

**Fig. 10**
Comparison of VE estimates against influenza B in those vaccinated in both seasons versus those vaccinated in the current season only

See this image and copyright information in PMC

References

1. World Health Organization Vaccines against influenza WHO position paper—November 2012. Wkly Epidemiol Rec. 2012;87(47):461–476. - PubMed
1. National Advisory Committee on Immunization . (NACI): Canadian Immunization Guide Chapter on Influenza and Statement on Seasonal Influenza Vaccine for 2017–2018. Ottawa: PHAC; 2017.
1. Hoskins T, Davies J, Smith A, Miller C, Allchin A. Assessment of inactivated influenza-A vaccine after three outbreaks of influenza A at Christ’s Hospital. Lancet. 1979;313(8106):33–35. doi: 10.1016/S0140-6736(79)90468-9. - DOI - PubMed
1. Keitel WA, Cate TR, Couch RB, Huggins LL, Hess KR. Efficacy of repeated annual immunization with inactivated influenza virus vaccines over a five year period. Vaccine. 1997;15(10):1114–1122. doi: 10.1016/S0264-410X(97)00003-0. - DOI - PubMed
1. Beyer WE, de Bruijn IA, Palache AM, Westendorp RG, Osterhaus AD. Protection against influenza after annually repeated vaccination: a meta-analysis of serologic and field studies. Arch Intern Med. 1999;159(2):182–8. - PubMed

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The impact of repeated vaccination on influenza vaccine effectiveness: a systematic review and meta-analysis

Affiliations

The impact of repeated vaccination on influenza vaccine effectiveness: a systematic review and meta-analysis

Authors

Affiliations

Abstract

Conflict of interest statement

Ethics approval and consent to participate

Consent for publication

Competing interests

Publisher’s Note

Figures

References

Publication types

MeSH terms

Substances

LinkOut - more resources

Full Text Sources

Other Literature Sources

Medical

Miscellaneous