A high-dose flu shot cut flu hospitalisations 8.8% in people with chronic lung disease

A high-dose flu vaccine cut hospital admissions for flu or pneumonia by 8.8% compared with a standard-dose shot among older adults with chronic lung disease, according to combined results from two randomized trials presented September 8, 2026 at the European Respiratory Society Congress in Barcelona. Dr. Lisa Steen Duus of Gentofte Hospital in Copenhagen, who presented the findings, said flu tends to hit this group harder than the general older population because pre-existing lung damage leaves less reserve to absorb a respiratory infection on top of it. Her team pooled data from two separate national trials to answer a question neither study alone was built to settle: does the extra-strength shot actually protect people whose lungs are already compromised.

The analysis drew on 466,320 total trial participants aged 65 and older, split roughly evenly between a standard-dose vaccine and one containing four times the antigen. Researchers then isolated everyone in that pool who also carried a chronic lung condition — asthma, bronchiectasis, bronchitis, chronic obstructive pulmonary disease, cystic fibrosis, emphysema, interstitial pulmonary disease, a prior lung transplant, respiratory tuberculosis or sarcoidosis — and tracked what happened to them from 14 days after vaccination through the following May.

Two National Trials Combined Data From 466,320 Patients

The pooled analysis merged DANFLU-2, a Danish trial that ran across the 2022-23, 2023-24 and 2024-25 flu seasons, with GALFLU, run in Galicia, Spain across the 2023-24 and 2024-25 seasons. Both are described by the European Respiratory Society as pragmatic, registry-based randomized trials, meaning participants were tracked through existing national health registries rather than through study-specific follow-up visits. That design let the combined dataset reach nearly half a million people, large enough to detect a modest but real difference in a subgroup that made up a small share of either trial on its own.

Earlier analysis of the same two trials already established that the high-dose vaccine benefits older adults broadly, a result Duus’s team built directly on rather than repeated. What the new analysis adds is a subgroup breakdown narrow enough to isolate people whose baseline hospitalization risk from flu is already elevated by lung disease.

Chronic Lung Disease Patients Made Up Just 7% of the Combined Cohort

Of the 466,320 people across both trials, 31,976 — just under 7% — had one of the ten qualifying chronic lung diagnoses. That is a small slice of a very large trial, but the researchers said it was enough to detect an 8.8% relative reduction in hospitalizations for flu or pneumonia among high-dose recipients compared with standard-dose recipients in that subgroup. The high-dose vaccine also lowered hospitalizations for cardiorespiratory disease and hospitalization from any cause during the same follow-up window, effects the release did not break out as separate percentages for the lung-disease group specifically.

Roughly half of the chronic-lung-disease participants were randomly assigned to each dose, the same one-to-one split used across the full trial population, which is what let researchers compare outcomes within the subgroup rather than simply extrapolating from the broader result.

A Quadruple-Strength Dose Targets a Weaker Immune Response in Older Adults

The high-dose formulation contains four times the active antigen of a standard flu shot, a design meant to compensate for immunosenescence — the well-documented decline in vaccine response that comes with age. The European Respiratory Society’s release on the pooled analysis frames the chronic-lung-disease finding as an extension of that same logic into a population researchers say has been understudied in randomized vaccine trials specifically, even though clinicians already suspected the group needed better protection.

Duus said the reassurance value extends beyond the hospital: “For older people with chronic lung disease and their families, these findings provide reassurance that high-dose flu vaccination can offer better protection against serious illness requiring hospital treatment than a standard-dose vaccine.” She added that even a modest reduction in hospitalizations carries weight given the burden each admission places on patients, families and health systems.

An Independent Reviewer Calls the Result Useful, Not Conclusive on Its Own

Professor Thomas Wilkinson of the University of Southampton, who chairs the European Respiratory Society’s group on respiratory infections and immunology and was not involved in the research, reviewed the pooled analysis independently. He noted that flu carries a heightened risk of severe illness, hospitalization and death specifically for older people with lung disease, which is why the society already recommends annual vaccination for that group regardless of dose. Coverage of Wilkinson’s comment describes him calling the pooled trials large and well-run, and their subgroup finding a signal that the high-dose option “could be even more beneficial” specifically for patients carrying a chronic lung diagnosis.

Neither DANFLU-2 nor GALFLU was originally designed around the chronic-lung-disease subgroup, so the 8.8% figure comes from a secondary analysis rather than a trial built from the ground up to test that population. Reporting on the combined results notes that a dedicated, prospectively designed trial in this subgroup has not yet been run, which leaves open exactly how the benefit might compare across specific lung diagnoses rather than the pooled group as a whole.

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This article was produced with the assistance of AI and reviewed by Morning Overview editors prior to publication.