Interim estimates reported for 2024-2025 seasonal influenza vaccine effectiveness in US patients

An interim observational report from the United States provided preliminary estimates of the 2024-2025 seasonal influenza vaccine effectiveness. The study population included patients in outpatient settings and hospitalized patients, with data collected from October 2024 through February 2025. The primary outcome was vaccine effectiveness in outpatient settings, with a secondary outcome assessing effectiveness against flu-associated hospitalizations. The comparator was not reported.

The main results indicate that interim vaccine effectiveness estimates were reported. However, the specific effect size, absolute numbers, p-values, confidence intervals, and direction of effect were not reported in this interim analysis. No data on safety, adverse events, serious adverse events, discontinuations, or tolerability were provided.

Key limitations include the preliminary nature of the interim estimates. The observational study design means findings show association, not causation. Specific practice relevance was not reported. Clinicians should interpret these interim estimates cautiously, as they lack the statistical detail needed for definitive conclusions and await final analysis.