Efficacy and effectiveness of high-dose versus standard-dose influenza vaccination for older adults: a systematic review and meta-analysis

ABSTRACT

Background: Influenza is responsible for a significant disease burden annually, especially in older adults. This study reviews the relative vaccine efficacy or effectiveness (rVE) of high-dose inactivated trivalent influenza vaccine (HD-IIV3) compared to standard-dose influenza vaccines (SD-IIV3) in adults ≥65 against influenza-associated outcomes to inform evidence-based decision-making to shift clinical practice and standard of care in this population.

Methods: A systematic review was conducted for studies assessing the rVE of HD-IIV3 against probable/laboratory-confirmed influenza-like illness (ILI), hospital admissions, and death in adults ≥65. Results from individual seasons were meta-analyzed and a random-effects model was used to estimate pooled rVEs.

Results: After screening 992 studies, seven studies were meta-analyzed. HD-IIV3 demonstrated better protection against ILI compared to SD-IIV3 (rVE = 19.5%; 95% CI: 8.6–29.0%). HD-IIV3 was also more effective at preventing hospital admissions from all-causes (rVE = 9.1%; 95% CI: 2.4–15.3%), as well as from influenza (rVE = 17.8%; 95% CI: 8.1–26.5%), pneumonia (rVE = 24.3%, 95% CI: 13.9–33.4%), and cardiorespiratory events (rVE = 18.2%; 95% CI: 6.8–28.1%). rVE against post-influenza mortality was 22.2% (95% CI: -18.2–48.8%) and 2.5% (95% CI: -5.2–9.5%) against all-cause mortality.

Conclusions: Available evidence suggests HD-IIV3 is more effective than SD-IIV3 at reducing the clinical outcomes associated with influenza infection in older adults and should be considered for routine use in the 65+ population.

KEYWORDS:

• High dose influenza vaccine
• influenza
• seniors
• elderly
• efficacy
• effectiveness
• hospitalization
• death
• systematic review
• meta-analysis

Author contributions

All authors contributed to study design, interpreted the results, and critically revised the manuscript. J Lee, G Lam, T Shin, J Kim, and A Krishnan conducted the systematic review; J Lee and G Lam conducted the meta-analyses and wrote the manuscript.

Declaration of interest

All authors were employees of Sanofi Pasteur during the conduct of the study. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose. A reviewer on this manuscript has disclosed participation with a Sanofi Pasteur advisory board on influenza vaccine.

Supplementary material

Supplementary material can be accessed here.

Additional information

Funding

This work was supported by Sanofi Pasteur.