This prespecified analysis will pool the datasets from two pragmatic randomized trials evaluating the relative vaccine effectiveness of high-dose vs. standard-dose influenza vaccine against severe clinical outcomes: the DANFLU-2 (A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults) trial and the GALFLU (Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Adults Aged 65 to 79 Years in Galicia, Spain) trial. The purpose of the pooled analysis is to ensure adequate statistical power for evaluating relative vaccine effectiveness against severe clinical outcomes and to increase generalizability of the results by combining data from two countries.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
NONE
Enrollment
466,320
For this arm, the high-dose quadrivalent influenza vaccine Efluelda®/Fluzone® High-Dose Quadrivalent will be used.
Any standard-dose quadrivalent influenza vaccine administered in the governmental influenza vaccine programs may be used.
Center for Translational Cardiology and Pragmatic Randomized Trials, Department of Cardiology, Copenhagen University Hospital - Herlev and Gentofte
Hellerup, Capital Region, Denmark
Hospitalization for influenza or pneumonia
Time frame: ≥14 days after vaccination up to 8 months
Hospitalization for any cardio-respiratory disease
Time frame: ≥14 days after vaccination up to 8 months
Laboratory-confirmed influenza hospitalization
Time frame: ≥14 days after vaccination up to 8 months
All-cause hospitalization
Time frame: ≥14 days after vaccination up to 8 months
All-cause mortality
Time frame: ≥14 days after vaccination up to 8 months
Hospitalization for influenza
Time frame: ≥14 days after vaccination up to 8 months
Hospitalization for pneumonia
Time frame: ≥14 days after vaccination up to 8 months
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