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

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 (& GE;65 years). The analysis included studies conducted over 12 influenza seasons (2009/2010 to 2019/2020, 2021/2022), including over 45 million individuals aged & GE; 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 & GE; 65 years, supported by observational data. & COPY; 2023 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Automated summary

This updated systematic review and meta-analysis 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 (& GE;65 years). The analysis included studies conducted over 12 influenza seasons and showed that HD-IIV provided significantly better protection than SD-IIV against influenza-related outcomes. Subgroup analyses further demonstrated the consistent superiority of HD-IIV across different age groups and strains of influenza.