NCT06567860

Characterizing Late-season Influenza Vaccine Responses to Compare the 2023 and 2024 Vaccine Formulations

• Status: Completed
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 23 (actual)
• Sponsor: La Jolla Institute for Immunology · Academic / Other
• Sex: All
• Age: 18 Years – 64 Years
• Healthy volunteers: Accepted

Summary

Every 1-2 years, the seasonal influenza vaccine composition changes to include updated viruses, yet the precise effects of updating the vaccine remain understudied. Since the vaccine formulation for each season (with a season defined as starting in July and ending the following June) expires on June 30, vaccine formulations cannot be compared head-to-head. Thus, the 2023 and 2024 vaccines have only been compared by analyzing people given the former vaccine in the fall of 2023 and people given the latter vaccine in the fall of 2024, and baseline repertoires may have greatly changed over the course of that year. To that end, the investigators will vaccinate a cohort with the 2023 influenza vaccine between May-June 2024, in order to compare responses between individuals receiving the 2023 vaccine last fall, the 2023 vaccine late in the season (this cohort), and the 2024 vaccine next fall. The investigators will further assess whether the late-season 2023 vaccine primed this cohort to respond better to the standard 2024 vaccine with standard timing (vaccine administered around September-October).

Conditions

• Influenza A

Interventions

Type	Name	Description
BIOLOGICAL	Influenza Fluzone vaccine	Fluzone vaccine administered in both May-June and in September-October for each participant.

Timeline

• Start date: 2024-05-21
• Primary completion: 2025-02-06
• Completion: 2025-02-06
• First posted: 2024-08-23
• Last updated: 2026-02-12
• Results posted: 2026-02-12

Locations

1 site across 1 country: United States

Regulatory

• FDA-regulated drug study