Skip to main content
OpenTrials
Completed

NCT Number: NCT06141655

HD vs SD Quadrivalent Influenza Vaccine in Adults Aged 65 to 79 Years in Galicia

This pragmatic randomized trial is designed to evaluate the relative vaccine effectiveness of QIV-HD vs. QIV-SD in reducing the risk of hospitalization for influenza or pneumonia in adults 65-79 years of age in Galicia during 2023/2024 and 2024/2025 seasons.

Completed

Looking for future studies?

Notify Me

Key information

Conditions

Influenza Infections Influenza, Human Orthomyxoviridae Infections RNA Virus Infections Respiratory Tract Diseases Respiratory Tract Infections Virus Diseases

Age range

65 year–79 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Phase 4

Primary location

General Public Health Directorate of Galician Health Service

Santiago de Compostela, A Coruña, Spain

About this study

The study is a pragmatic, registry-based, open-label, active-controlled, individually randomized trial using the infrastructure of the Regional Vaccination Program of Galicia for patient recruitment, inclusion, randomization, and vaccine administration and the Galician health registries for data collection including baseline information, follow-up data and safety monitoring. Participants will have the opportunity of receiving all the information for the trial prior to the vaccination appointment. Informed consent will be obtained during the vaccination appointment by the study team prior to their vaccine administration. The participation in the study is voluntary, and only individuals who accept signing the informed consent will be recruited. Participants may withdraw from the study at any point.

The study aims to randomize at least 114.011 participants over 2 influenza seasons (2023/2024 and 2024/2025) with approximately 57,000 participants per season (pending any further potential sample size adjustments following interim analysis).

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • 1. Age 65-79 years residing in the community (only individuals who are not eligible to receive QIV-HD as part of the standard of care)
  • 2. Informed consent form has been signed and dated

Exclusion criteria

  • There are no specific exclusion criteria for this study

Treatment and study plan

Influenza vaccine

Drug

Participants will be individually randomized 1:1 to receive either QIV-HD or QIV-SD, one dose, the day of the inclusion in the trial

Primary outcomes

  1. Occurrence of a hospitalization due to influenza or pneumonia

    Time frame: ≥14 days after vaccination and up to May 31 the following year

Secondary outcomes

  1. Hospitalization for any cardio-respiratory disease [composite endpoint]

    Time frame: ≥14 days after vaccination and up to May 31 the following year

  2. All-cause hospitalization

    Time frame: ≥14 days after vaccination and up to May 31 the following year

  3. All-cause mortality

    Time frame: ≥14 days after vaccination and up to May 31 the following year

  4. Hospitalization for influenza

    Time frame: ≥14 days after vaccination and up to May 31 the following year

  5. Hospitalization for pneumonia

    Time frame: ≥14 days after vaccination and up to May 31 the following year

Sponsors and collaborators

Lead sponsor

Federico Martinón Torres

Other

Registry information

Official study title

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

Important dates

Study start
2023
Primary completion
2025
Study completion
2025
First posted
Nov 21, 2023
Registry last updated
Aug 8, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Related clinical trials

Published trials that share one or more normalized conditions with this study.