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Immunogenicity of Twice-annual Influenza Vaccination in Older Adults in Hong Kong

Study acronym: RETAIN
StatusUnknown
PhasePhase 4
Started
View on ClinicalTrials.gov ↗
Record status
This record was last updated December 11, 2023 (before its estimated September 2025 completion). Its status may not reflect the trial's current state.

Record History

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  1. Changed Registry marked status Unknown (sponsor has not verified the record since Dec 2023); last known: Active, Not Recruiting
  2. Re-verified, no change to tracked fieldsv6
  3. Primary completion date: Sep 2021 to Sep 2025
    • Study completion date: Sep 2022 to Sep 2026
    • Study description expanded, about 23 words
    v5
  4. Trial status: Recruiting to Active, Not Recruiting
    • Site details revised
    v4
  5. Trial status: Not Yet Recruiting to Recruiting
    • Start date: Nov 2016 to Nov 18, 2016
    • Site details revised
    v3
  6. Primary endpoints: 2 to 1
    • Study description expanded, about 2 words
    v2
  7. Study First Submitted
  • Stopped: an ongoing trial was terminated, suspended or withdrawn.
  • Notable: the trial’s plan changed such as a big move in its timeline or size, a new primary endpoint, sponsor or phase, or recruiting opened or resumed.
  • Minor: routine progress and housekeeping, such as sites added or enrollment closed.
This study evaluates the immunogenicity of adding inactivated influenza vaccine with southern hemisphere (SH) formulation to standard once-annual influenza vaccination with northern hemisphere (NH) formulation in older adults in Hong Kong over 9 years. Half of participants will receive twice-annual influenza vaccination with NH and SH formulation, while the other half will receive once-annual influenza vaccination with NH formulation and a placebo.
Trial Details
NCT Number NCT02957890
Lead Sponsor The University of Hong Kong
Collaborators: Centers for Disease Control and Prevention, Hospital Authority, Hong Kong
Conditions
(from sponsor)		 Influenza, Human
Related terms Influenza, Human
Enrollment 400 participants
Start Date
Primary Completion (estimated)
Study Completion (estimated)
Updated on ClinicalTrials.gov