High-dose influenza vaccine in older adults by age and seasonal characteristics: Systematic review and meta-analysis update

Jason K H Lee; Gary K L Lam; J Kevin Yin; Matthew M Loiacono; Sandrine I Samson

doi:10.1016/j.jvacx.2023.100327

High-dose influenza vaccine in older adults by age and seasonal characteristics: Systematic review and meta-analysis update

Vaccine X. 2023 Jun 5:14:100327. doi: 10.1016/j.jvacx.2023.100327. eCollection 2023 Aug.

Authors

Jason K H Lee^{1

2}, Gary K L Lam^{1

2}, J Kevin Yin^{3

4}, Matthew M Loiacono⁵, Sandrine I Samson⁶

Affiliations

¹ Leslie Dan School of Pharmacy, University of Toronto, Toronto, ON, Canada.
² Sanofi, Toronto, ON, Canada.
³ University of Sydney, Camperdown, NSW, Australia.
⁴ Sanofi, Singapore.
⁵ Sanofi, Swiftwater, PA, USA.
⁶ Sanofi, Lyon, France.

Abstract

This updated systematic review and meta-analysis of randomized and observational studies published up to April 2023 assessed the relative performance of high-dose inactivated influenza vaccine (HD-IIV) and standard-dose influenza vaccines (SD-IIV) against influenza-associated outcomes in older adults (≥65 years). The analysis included studies conducted over 12 influenza seasons (2009/2010 to 2019/2020, 2021/2022), including over 45 million individuals aged ≥ 65 years, and showed that HD-IIV provided significantly better protection than SD-IIV against influenza-like illness and influenza-related hospitalizations, as well as cardiovascular, cardiorespiratory, and all-cause hospitalizations. Subgroup analyses showed HD-IIV consistently provided better protection than SD-IIV against influenza outcomes across the age range (65+, 75+ 85+ years), and regardless of the predominantly circulating influenza strain and vaccine antigenic match/mismatch. Randomized studies continue to drive high-quality evidence on the effectiveness of high-dose inactivated influenza vaccine relative to SD-IIV against severe influenza outcomes in adults aged ≥ 65 years, supported by observational data.

Keywords: Effectiveness; Elderly; High dose influenza vaccine; Hospitalization; Influenza; Meta-analysis.