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. 2021 Feb 5;8(3):ofab069.
doi: 10.1093/ofid/ofab069. eCollection 2021 Mar.

Decline in Seasonal Influenza Vaccine Effectiveness With Vaccination Program Maturation: A Systematic Review and Meta-analysis

George N Okoli  1   2   3 , Florentin Racovitan  2 , Tiba Abdulwahid  3 , Syed K Hyder  4 , Louise Lansbury  4 , Christiaan H Righolt  2   5 , Salaheddin M Mahmud  1   2   5 , Jonathan S Nguyen-Van-Tam  4
Affiliations

Decline in Seasonal Influenza Vaccine Effectiveness With Vaccination Program Maturation: A Systematic Review and Meta-analysis

George N Okoli et al. Open Forum Infect Dis. .

Abstract

Background: Evidence suggests that repeated influenza vaccination may reduce vaccine effectiveness (VE). Using influenza vaccination program maturation (PM; number of years since program inception) as a proxy for population-level repeated vaccination, we assessed the impact on pooled adjusted end-season VE estimates from outpatient test-negative design studies.

Methods: We systematically searched and selected full-text publications from January 2011 to February 2020 (PROSPERO: CRD42017064595). We obtained influenza vaccination program inception year for each country and calculated PM as the difference between the year of deployment and year of program inception. We categorized PM into halves (cut at the median), tertiles, and quartiles and calculated pooled VE using an inverse-variance random-effects model. The primary outcome was pooled VE against all influenza.

Results: We included 72 articles from 11 931 citations. Across the 3 categorizations of PM, a lower pooled VE against all influenza for all patients was observed with PM. Substantially higher reductions were observed in older adults (≥65 years). We observed similar results for A(H1N1)pdm09, A(H3N2), and influenza B.

Conclusions: The evidence suggests that influenza VE declines with vaccination PM. This study forms the basis for further discussions and examinations of the potential impact of vaccination PM on seasonal VE.

Keywords: seasonal influenza; systematic review; test-negative design; vaccination program; vaccine effectiveness.

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Figures

Figure 1.
Figure 1.
Modified Preferred Reporting Items for Systematic Reviews and Meta-Analysis flowchart (study selection process).
Figure 2.
Figure 2.
Forest plot of vaccine effectiveness (VE) against all influenza across Q2 category (all patients: studies with antigenically similar vaccine). Less than median = lower half of the sorted data; more than median = higher half of the sorted data.
Figure 3.
Figure 3.
Forest plot of vaccine effectiveness (VE) against all influenza across Q3 category (all patients: studies with antigenically similar vaccine).
Figure 4.
Figure 4.
Forest plot of vaccine effectiveness (VE) against all influenza across Q4 category (all patients: studies with antigenically similar vaccine).
See this image and copyright information in PMC

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