Study: High-Dose Flu Vaccine Reduces Hospitalization and Infection Risks

Basio badr

ago 3 hours

Study: High-Dose Flu Vaccine Reduces Hospitalization and Infection Risks

Recent studies have highlighted the significant advantages of high-dose influenza vaccines in reducing hospitalization and infection risks, particularly among older adults. These findings are expected to guide health policy decisions and vaccination strategies globally.

High-Dose Flu Vaccine More Effective Against Hospitalization

The first analysis, published in The Lancet, examined the efficacy of the high-dose inactivated influenza vaccine (HD-IIV) compared to the standard-dose (SD-IIV). Conducted by an international team, including researchers from Sanofi, this study pooled data from two substantial clinical trials: DANFLU-2 (Denmark, 2022-2025) and GALFLU (Spain, 2023-2025).

Study Details

Participants: 466,320 adults with an average age of 73.3 years, 48% women, and 48.9% with chronic conditions.
Key Findings:

Hospitalization rates for flu or pneumonia: 0.56% in HD-IIV group vs. 0.62% in SD-IIV group (relative vaccine effectiveness [rVE] of 8.8%).
Reduced risk of cardiorespiratory hospitalization: 2.02% vs. 2.16% (rVE of 6.3%).
Lower flu hospitalization rate: 0.11% in HD-IIV vs. 0.16% in SD-IIV (rVE of 31.9%).

Notably, approximately 515 older adults would need to switch from SD-IIV to HD-IIV to prevent one all-cause hospitalization. This indicates that HD-IIV could significantly alleviate the burden of influenza on healthcare systems.

High-Dose Vaccine Offers Greater Protection Against Infection

The second study, highlighted in the International Journal of Infectious Diseases, focused on infection rates among older adults vaccinated during the 2022-2023 and 2024-2025 flu seasons. It analyzed data from four studies and utilized a test-negative design.

Key Analysis Points

Participants: Average age 81.1 years, 52.1% women, and 87.2% had at least one chronic condition.
Flu Cases Identified: 102 cases (8.2%), primarily type A influenza.
Infection Rates: 6.6% for HD-IIV recipients vs. 10.3% for SD-IIV (rVE of 29%).

The high-dose vaccine demonstrated a 54% higher effectiveness against infection for adults aged 80 and over. In contrast, the overall rVE of HD-IIV was 40% when considering unadjusted estimates.

The authors suggest that these results could influence vaccination practices, emphasizing the need for healthcare providers and policymakers to consider high-dose vaccines in their immunization strategies for vulnerable populations. The increased effectiveness of high-dose influenza vaccines provides compelling evidence for their adoption and could lead to improved health outcomes among older adults worldwide.