Elderly adults who received a high-dose quadrivalent influenza vaccine compared with a standard dose had a significantly reduced risk of death and hospitalization for influenza or pneumonia, based on findings from the DANFLU-1 trial presented during ESC Congress 2022.

The innovative, feasibility trial out of Denmark enrolled 12,477 patients (median age 71.7 years; 47.1% women) who were randomly assigned to receive either a high-dose vaccine (n=6,245) or a standard-dose vaccine (n=6,232). The trial was integrated into the Danish vaccination program, with only one study visit at the time of vaccination and registry-based follow-up occurring thereafter.

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Overall, the high-dose influenza vaccine was associated with a 49% reduction in the risk of death and a 64% reduction in the incidence of hospitalization for influenza or pneumonia compared with a standard-dose vaccination. No significant differences in serious adverse events were observed between the high-dose and standard-dose groups.

In presenting the findings, Tor Biering-Sørensen, MD, PhD, MPH, said DANFLU-1 not only hints at the benefits in morbidity and mortality of a high-dose influenza vaccine, but also shows that "conducting an innovative pragmatic randomized trial in Denmark using administrative health registries as the primary data source is feasible." He said that "the next step is to conduct a fully powered trial of high-dose versus standard-dose quadrivalent influenza vaccine in older adults," which will require around 200,000 participants.