Table of contents
- Trial overview
- Studied groups and conditions
- Trial designs and phases
- Main endpoints
- What the trials compare
- Patient-friendly terms
Trial overview
The source data describe several clinical trials that investigate influenza vaccines, including studies linked to INFLUENZA A VIRUS, A/CROATIA/10136RV/2023 (H3N2) LIKE STRAIN X-425A, INACTIVATED as part of broader influenza vaccine research.[1] These studies focus on how the immune system responds after vaccination, not on treating active flu illness.[1]
All listed trials are Phase 3 studies, which means they are testing vaccines in larger groups of people and measuring immune response outcomes.[1][2]
Studied groups and conditions
The trials target different groups, including adults seeking active immunisation against seasonal influenza, people with obesity, and people involved in avian influenza and seasonal influenza vaccine research.[2][3][4]
One study also includes participants with type 2 diabetes, showing that researchers are interested in vaccine response in people with health conditions that may affect immunity.[4]
The conditions listed across the trials are influenza, seasonal influenza, avian influenza, obesity, and type 2 diabetes.[1][2][3][4]
Trial designs and phases
All four studies in the source data are interventional, meaning researchers give a vaccine and then measure the body’s response.[1][2][3][4]
The studies include both authorised and completed trials, with enrolment sizes ranging from 30 to 300 participants.[1][2][3][4]
NCT05921448 is a randomized controlled Phase 3 trial with 55 participants.[1] It compares nasal live attenuated influenza vaccine with intramuscular influenza vaccine and a placebo control.[1]
2023-509178-44-00 is a Phase 3 study with 300 participants that examines immune responses to customized avian influenza vaccine and seasonal influenza vaccine options.[2]
2025-521217-46-00 is a completed Phase 3 study with 30 participants that looks at nasal and respiratory memory immune responses after influenza vaccination.[3]
2025-522698-13-00 is an authorised Phase 3 study with 100 participants that evaluates vaccine immune response in obesity, including participants with type 2 diabetes.[4]
Main endpoints
The main outcomes are immune response measures, not symptom relief or treatment of active infection.[1][2][3][4]
Antigen activated CD4+ T-lymphocytes are measured in one study before and after vaccination, at several time points up to day 90.[1] These are immune cells that help the body respond to a vaccine.
Mucosal antibody titer is measured in respiratory secretions in one study to see whether antibodies rise after vaccination.[1] Mucosal means the lining of the nose and airways.
Seroconversion proportion is the main outcome in the avian influenza study, measured three weeks after the second dose using the microneutralization test.[2] This shows how many participants develop a clear immune response.
Resident memory lymphocytes in the nasal mucosa and peripheral memory lymphocytes with respiratory tropism are measured before and after vaccination in another study.[3] These cells can help the body respond quickly if flu exposure happens later.
Hemagglutination inhibition assay results are measured in the obesity study at day 0 and 14 days after vaccination.[4] The study looks at geometric mean titres, the share of people with a protective titre of 40 or more, and the share with a four-fold rise in titre.[4]
What the trials compare
Some studies compare different vaccine types, such as nasal live attenuated influenza vaccine versus intramuscular inactivated influenza vaccine.[1] Others compare immune responses after customized avian influenza vaccine and standard seasonal influenza vaccines.[2]
The completed study in adults focuses on how influenza vaccination changes immune cells in the nose and respiratory system over time.[3] The obesity study looks at whether people with obesity, with or without type 2 diabetes, show strong antibody responses after vaccination.[4]
Patient-friendly terms
Humoral immunity means the part of the immune system that makes antibodies in blood and body fluids.[1][2][4]
Cell-mediated immunity means protection made by immune cells, especially T cells, rather than antibodies alone.[1][2]
Intramuscular injection means the vaccine is given into a muscle, usually in the arm.[1][2][3][4]
Nasal spray means the vaccine is given through the nose instead of by injection.[1]
Placebo means a control product that does not contain the active vaccine being studied.[1]
Randomized controlled trial means participants are assigned by chance to different study groups so the results can be compared fairly.[1]
