High-Dose vs Standard-Dose Influenza Vaccine in Chronic Kidney Disease: The DANFLU-2 Trial Subgroup Analysis
Authors' conclusion
In this prespecified analysis of DANFLU-2, including the largest CKD population ever in an individually randomized vaccine trial, we observed a benefit of HD-IIV vs SD-IIV against hospitalization for influenza or pneumonia, as well as hospitalization for influenza, with suggestion of a greater relative benefit among those with CKD.
Study context
- Population
- Older adults in Denmark, 2022–2023 to 2024–2025 influenza seasons, by presence of chronic kidney disease (CKD)46,788 (14.1%) with CKD
- Participants
- 332,438 adults
- Comparison
- High-dose inactivated influenza vaccine (HD-IIV) vs standard-dose inactivated influenza vaccine (SD-IIV), by CKD status
- Primary endpoint
- Hospitalization for influenza or pneumonia (rVE), by CKD status
Methodological detailsprespecified secondary analysis, pragmatic, open-label, individually randomized
- Prespecified secondary analysis
- Pragmatic
- Open-label
- Individually randomized
Primary result
As reported in the abstract
Hospitalization for influenza or pneumonia
HD-IIV vs SD-IIVAbsolute risk reduction (95% CI)
CKD; NNT = 359
−0.29%(−0.50% to 0.058%)
Relative effectiveness (rVE)
- CKD
- 16.9% (95% CI 3.4%–28.5%)
- No CKD
- 0.6% (95% CI −9.6% to 9.9%)
Further findings
| Outcome | rVE (95% CI) |
|---|---|
| Influenza hospitalization, by CKD statusHD-IIV vs SD-IIV · CKD; NNT = 561 | 68.6% (46.7%–82.3%) |
| Influenza hospitalization, by CKD statusHD-IIV vs SD-IIV · no CKD; NNT =3,953 | 30.6% (7.2%–48.2%) |
- Influenza hospitalization, by CKD status: P interaction = 0.0079
Hospitalization for cardiorespiratory disease, CVD, HF, laboratory-confirmed influenza
- Reductions consistent regardless of CKD
- all P interaction > 0.05
Original publication
High-Dose vs Standard-Dose Influenza Vaccine in Chronic Kidney Disease: The DANFLU-2 Trial Subgroup Analysis. J Am Coll Cardiol. Published 26 November 2025. doi:10.
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