A Pragmatic Randomized Trial to Evaluate the Effectiveness of High-Dose Quadrivalent Influenza Vaccine vs. Standard-Dose Quadrivalent Influenza Vaccine in Older Adults (DANFLU-2)

Tor Biering-Sørensen

Status and phase: Completed; Phase 4

Conditions: Influenza

Treatments: Biological: High-Dose Quadrivalent Influenza Vaccine; Biological: Standard-Dose Quadrivalent Influenza Vaccine

Study type: Interventional

Funder types: Other; Industry

Identifiers

NCT05517174

DANFLU-2

2022-500657-17-00 (Other Identifier)

Details and patient eligibility

About

The purpose of this pragmatic randomized trial is to evaluate the relative vaccine effectiveness of high-dose quadrivalent influenza vaccine (QIV-HD) vs. standard-dose quadrivalent influenza vaccine (QIV-SD) in older adults. Participants will be randomized 1:1 to either QIV-HD or QIV-SD.

Full description

The study is a pragmatic, registry-based, open-label, active-controlled, individually randomized trial. The Danish nationwide administrative health registries will be used for data collection including baseline information, follow-up data, and safety monitoring. The study aims to randomize 339,700 participants over 3 influenza seasons. In each season, participants will be individually randomized 1:1 to receive either QIV-HD or QIV-SD. During the 2023/2024 and 2024/2025 seasons, up to 12,000 participants will be enrolled in a sub-cohort where participants are asked to perform home self-swabs and answer symptom questionnaires in case of influenza-like illness to enable further assessment of the impact of QIV-HD vs. QIV-SD on patient-reported outcomes among individuals with influenza-like illness and laboratory-confirmed influenza.

Enrollment: 332,438 patients

Sex: All

Ages: 65+ years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Age 65 years and above (this inclusion criterion will be modified according to the Danish government's official recommendations for the 2022/2023 and 2023/2024 influenza seasons)
• Informed consent form has been signed and dated

Exclusion criteria

• There are no specific exclusion criteria for this study

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: None (Open label)

---

332,438 participants in 2 patient groups

High-Dose Quadrivalent Influenza Vaccine

Experimental group

Description:

QIV-HD single injection at Day 0

Treatment:

Biological: High-Dose Quadrivalent Influenza Vaccine

Standard-Dose Quadrivalent Influenza Vaccine

Active Comparator group

Description:

QIV-SD single injection at Day 0

Treatment:

Biological: Standard-Dose Quadrivalent Influenza Vaccine