Recent research highlights the superior efficacy of the high-dose influenza vaccine (HD-IIV) compared to the standard-dose version (SD-IIV) in protecting older adults from hospitalization and infection related to influenza.
Study Insights on High-Dose Flu Vaccine
Two comprehensive studies provide compelling evidence that HD-IIV offers significant advantages over the standard formulation. The first study, published in The Lancet, focused on the hospitalization rates of older adults receiving HD-IIV versus SD-IIV.
Key Findings from the First Study
- The research included pooled data from two major trials: DANFLU-2 conducted in Denmark (2022-2025) and GALFLU in Spain (2023-2025).
- A total of 466,320 older adults participated, with an average age of 73.3 years; 48% were women.
- The study found that HD-IIV reduced hospitalization rates for flu or pneumonia to 0.56%, compared to 0.62% for SD-IIV.
- Importantly, HD-IIV was 40% more effective in preventing hospitalization overall.
- To prevent one all-cause hospitalization, approximately 515 older adults need to receive the HD-IIV.
The study results underscored the potential for the HD-IIV to ease the burden of influenza on health care systems worldwide. Researchers emphasized that transitioning to HD-IIV could substantially lower hospitalization rates in vulnerable populations.
Focus on Cardiorespiratory and Flu Hospitalizations
- Cardiorespiratory hospitalization rates were 2.02% in the HD-IIV group versus 2.16% in the SD-IIV cohort.
- Flu hospitalizations were 0.11% for HD-IIV compared to 0.16% for SD-IIV, indicating an rVE of 31.9% in favor of HD-IIV.
- Similar hospitalization rates for pneumonia were observed at 0.50% for HD-IIV and 0.51% for SD-IIV.
Enhanced Protection Against Infection
The second study, published in the International Journal of Infectious Diseases, utilized a test-negative design to assess infection rates among older adults vaccinated during the 2022-2023 and 2024-2025 flu seasons.
Key Findings from the Second Study
- The analysis involved 1,238 older adults, aged an average of 81.1 years; 52.1% were women.
- Participants vaccinated with HD-IIV confirmed lower influenza positivity rates (6.6%) compared to those receiving SD-IIV (10.3%).
- Among adults aged 80 years and older, HD-IIV proved 54% more effective against influenza infection.
The study identified a total of 102 flu cases, mainly of type A influenza, affirming the HD-IIV’s effectiveness in reducing laboratory-confirmed episodes compared to SD-IIV.
Conclusion
The findings from both studies indicate that high-dose influenza vaccines can significantly reduce hospitalization and infection rates in older populations. As health care providers and policymakers consider vaccination strategies, the HD-IIV emerges as a critical tool for enhancing immunity in vulnerable groups.
