InfluenzaPhase 4NCT07854392
A Study to Evaluate the Immune Responses of Subunit Influenza Vaccine in Healthy Adults
A Phase 4 study testing Group A and Group B in people with Influenza, run by Ab&B Bio-tech Co., Ltd.JS at 1 site in China.
Trial summary
This is a prospective, open-label, parallel time-cohort study designed to characterize the humoral and cellular immune responses induced by a subunit influenza vaccine (manufactured by Ab\&B Bio-tech Co., Ltd.JS) in healthy adults within one month after vaccination. Read more about this study
- Who is it for?
- Ages 18 to 59 yearsHealthy volunteers can take part
- Conditions the study is for
- Influenza
- What is being tested?
- Group A and Group B
- Type of treatment
- Vaccines
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 138 participants
- Where
- 1 siteChina
- Study dates
- 10 Oct 2026to 11 Oct 2027
- Phase
- Phase 4
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 59 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Adults aged between 18 and 59 years at the time of informed consent signature.
- Judged by the investigator to be in good health, based on medical history and physical examination findings obtained at screening.
- Able to comprehend and voluntarily provide written informed consent, and willing to comply with all study procedures and requirements.
Who cannot join
- Known allergy to any component of the vaccine, including excipients, formaldehyde, or Triton N-101.
- Confirmed influenza infection or influenza-like illness within the past 6 months, or close contact with a confirmed influenza case within 14 days prior to the screening visit.
- Receipt of any influenza vaccine (licensed or investigational) within the past 6 months.
- Receipt of any licensed vaccine within 28 days prior to study vaccination, or planned receipt of any licensed vaccine within 28 days after study vaccination.
- Receipt of blood products or immunoglobulin within the past 3 months, or planned receipt within 1 month after study vaccination.
- Female participants who are known to be pregnant or breastfeeding; female participants of childbearing potential with a positive pregnancy test at screening; or those planning pregnancy within the next 3 months.
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- Presence of acute illness, acute exacerbation of a chronic disease, or fever (axillary temperature ≥37.3 °C) within 3 days prior to vaccination. Use of anti-inflammatory, antibiotic, anti-allergic, or antiviral medications within 3 days prior to vaccination due to illness, including but not limited to acetaminophen, ibuprofen, loratadine, penicillins, cephalosporins, ribavirin, oseltamivir, and acyclovir.
- Systolic blood pressure ≥140 mmHg and/or diastolic blood pressure ≥90 mmHg on the day of vaccination.
- Severe chronic cardiovascular or pulmonary disease:
- Heart failure with a history of acute exacerbation within the past 2 years;
- Chronic obstructive pulmonary disease (COPD) with a history of acute exacerbation within the past 2 years;
- Chronic interstitial lung disease with acute exacerbation or requirement for treatment adjustment within the past 2 years;
- - History of asthma exacerbation within the past 2 years, or worsening asthma symptoms requiring adjustment of controller medication within the past 2 months;
- Uncontrolled serious arrhythmia, or hospitalization for acute arrhythmia or regular antiarrhythmic medication within the past 6 months;
- Unstable coronary artery disease within the past 3 months, as evidenced by percutaneous coronary intervention (e.g., stent implantation), coronary artery bypass grafting (CABG), newly initiated cardiac medication for symptom control, or unstable angina.
- Uncontrolled epilepsy or other progressive neurological diseases (e.g., multiple sclerosis, dementia, Parkinson's disease, neurodegenerative disorders, neuropathy); History of Guillain-Barré syndrome; Stroke with residual neurological deficits within the past 12 months; Any other neurological disease with residual symptoms within the past 12 months.
- Currently receiving anti-tumor therapy, including chemotherapy/radiotherapy, targeted therapy, or immunotherapy; Recurrence or metastasis of malignancy within the past 12 months; History of solid organ transplantation or hematopoietic stem cell transplantation.
- Chronic conditions potentially affecting study outcomes:
- Diagnosed hypertension or diabetes mellitus;
- Symptoms of myocarditis or pericarditis;
- Anemia, thrombocytopenia, or other coagulation disorders;
- Gout with joint redness and swelling, or use of systemic corticosteroids, high-dose colchicine, or non-steroidal anti-inflammatory drugs (NSAIDs) within the past month;
- Autoimmune diseases (e.g., systemic lupus erythematosus, rheumatoid arthritis, systemic vasculitis);
- Severe immunodeficiency, or requirement for immunosuppressive or corticosteroid therapy during the study period, or any medical history associated with impaired immunity (e.g., HIV infection, malignancy, particularly leukemia or lymphoma, history of radiation therapy, or use of immunosuppressive or anti-neoplastic agents);
- Chronic kidney disease/renal insufficiency, or chronic gastrointestinal and hepatic diseases (e.g., chronic gastritis, irritable bowel syndrome [IBS], inflammatory bowel disease [IBD], Crohn's disease, colitis, hepatitis B, hepatitis C, non-alcoholic fatty liver disease, cirrhosis, hepatocellular carcinoma) requiring regular medication;
- Uncontrolled allergic diseases (e.g., allergic asthma, allergic rhinitis). Presence of active, unhealed systemic or extensive cutaneous allergic conditions at screening, including but not limited to allergic dermatitis, severe eczema, urticaria, acute flare of psoriasis, or exfoliative dermatitis. Frequent episodes of unexplained pruritus, rash, or wheals within the past month, or unstable skin allergic conditions requiring continuous antihistamine therapy, as judged by the investigator to make the participant unsuitable for enrollment.
- Planned relocation outside the study site area before completion of all study procedures, or anticipated prolonged absence during scheduled follow-up visits that would prevent completion of the study schedule.
- Currently enrolled in any other clinical trial, or planning to participate in another clinical trial before completion of the present study.
- Any other condition or circumstance that, in the investigator's opinion, renders the participant unsuitable for enrollment.
Trial locations and contacts
1 site in 1 country.
China1 site
Shangyu District Center for Disease Control and Prevention
Shaoxing, Zhejiang, 312000
About this study
Official title: A Phase IV, Prospective, Open-label, Parallel Time-cohort Study to Evaluate the Immune Responses and Safety ofSubunit Influenza Vaccine in Healthy Adults
This is a prospective, open-label, parallel time-cohort study designed to characterize the humoral and cellular immune responses induced by a subunit influenza vaccine (manufactured by Ab\&B Bio-tech Co., Ltd.JS) in healthy adults within one month after vaccination. Eligible participants will receive a single intramuscular dose and will be assigned in parallel to one of two blood-sampling schedules to capture the kinetic profile of the immune response: Group A (pre-vaccination, Day 5, and Day 14 post-vaccination) and Group B (pre-vaccination, Day 7, and Day 21 post-vaccination). Hemagglutination inhibition (HI) antibody titers will be measured to assess humoral immunity, while circulating CD4⁺ and CD8⁺ T-cell levels will be analyzed to evaluate cellular immunity. The occurrence of adverse events（AEs) and serious adverse events(SAEs) within 28 days post-vaccination will be recorded.
Read the detailed description
Study Objectives The primary objective of this study is to describe the time course of humoral and cellular immune responses within one month after a single dose of the subunit influenza vaccine in healthy adults. Secondary objectives include: (1) exploring the onset time window of vaccine-induced immunity; (2) evaluating the immunogenicity of the vaccine as measured by HI antibody seroconversion and T-cell subset dynamics; and (3) assessing the safety of the vaccine during the 28-day post-vaccination surveillance period.
Study Design
This is a prospective, open-label, parallel time-cohort study. Enrolled participants will receive one intramuscular injection of the study vaccine into the lateral aspect of the upper deltoid. Participants will be assigned in parallel to one of two sampling cohorts, each comprising three study visits:
- Group A: Venous blood collected at three time points - Day 0 (pre-vaccination), Day 5, and Day 14 post-vaccination.
- Group B: Venous blood collected at three time points - Day 0 (pre-vaccination), Day 7, and Day 21 post-vaccination.
At each visit, approximately 20 mL of venous blood will be drawn. Of this, 5 mL will be collected in a non-anticoagulant tube for serum separation and hemagglutination inhibition (HI) antibody testing, and 15 mL will be collected in an anticoagulant tube for peripheral blood mononuclear cell (PBMC) isolation and subsequent flow cytometric analysis of CD4⁺ and CD8⁺ T-cell populations.
Study Population Healthy adults who meet the eligibility criteria, including a complete medical history, physical examination, and screening laboratory results.
Safety Monitoring All participants will remain under direct medical observation for at least 30 minutes immediately after vaccination. The occurrence of adverse events (AEs) and serious adverse events (SAEs) within 28 days post-vaccination will be collected and recorded, including solicited local reactions (pain, swelling, erythema, induration, pruritus, ecchymosis) and systemic events (fever, cough, headache, fatigue, myalgia, arthralgia, gastrointestinal symptoms, rash, etc.).
Ethics The study has been reviewed and approved by the Ethics Review Committee of Zhejiang Provincial Center for Disease Control and Prevention. All participants will provide written informed consent prior to study enrollment. Participation is voluntary, and participants may withdraw at any time without penalty.
- Conditions
- Influenza
- Being tested
- Group A, Group B
- Keywords
- Influenza, Human, Immune Response, Safety, Healthy Adults, Subunit Influenza Vaccine
- Medical subject headings
- Influenza, Human
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Group ABiological
Participants will receive one dose of Subunit Influenza Vaccine
Group BBiological
Participants will receive one dose of Subunit Influenza Vaccine
| Study group | Role | What they receive |
|---|---|---|
| Group A | Experimental | Not described Receives: Biological: Group A |
| Group B | Experimental | Not described Receives: Biological: Group B |
What is being measured
The primary outcome is the main question the study is designed to answer.
GMTs of HI antibodies against the three vaccine strains (Group B, Day 21 post-vaccination)
Influenza A includes H1N1 and H3N2; influenza B includes Victoria-lineage. Geometric mean HI antibody titer for each strain will be calculated with two-sided 95% CIs.
Measured: Day 21 post-vaccination (Group B)
GMIs of HI antibodies against the three vaccine strains (Group B, Day 21 post-vaccination)
Geometric mean fold increase in HI antibody titer from pre-vaccination (Day 0) to Day 21 for each strain, with two-sided 95% CIs.
Measured: Day 21 post-vaccination (Group B)
SCRs of HI antibodies against the three vaccine strains (Group B, Day 21 post-vaccination)
Seroconversion is defined as either a pre-vaccination HI titer <1:10 with a post-vaccination titer ≥1:40, or a pre-vaccination HI titer ≥1:10 with at least a four-fold increase in titer.
Measured: Day 21 post-vaccination (Group B)
SPRs of HI antibodies against the three vaccine strains (Group B, Day 21 post-vaccination)
Seroprotection is defined as an HI titer ≥1:40.
Measured: Day 21 post-vaccination (Group B)
Secondary outcomes (7)
GMTs of HI antibodies against the three vaccine strains (Group A, Day 5 and Day 14 post-vaccination)
Influenza A includes H1N1 and H3N2; influenza B includes Victoria-lineage. GMTs will be calculated for each strain at Day 5 and Day 14 in Group A.
Measured: Day 5 and Day 14 post-vaccination (Group A)
GMTs of HI antibodies against the three vaccine strains (Group B, Day 7 post-vaccination)
Influenza A includes H1N1 and H3N2; influenza B includes Victoria-lineage. GMTs will be calculated for each strain at Day 7 in Group B.
Measured: Day 7 post-vaccination (Group B)
Antigen-specific CD4⁺ T-cell counts and proportions (Group A: Day 0, Day 5, Day 14; Group B: Day 0, Day 7, Day 21)
Number and percentage of antigen-specific CD4⁺ T cells will be measured by flow cytometry at all three time points in Group A and Group B.
Measured: Day 0, Day 5, Day 14 (Group A); Day 0, Day 7, Day 21(Group B:)
Antigen-specific CD8⁺ T-cell counts and proportions (Group A: Day 0, Day 5, Day 14; Group B: Day 0, Day 7, Day 21)
Number and percentage of antigen-specific CD8⁺ T cells will be measured by flow cytometry at all three time points in Group A and Group B.
Measured: Day 0, Day 5, Day 14 (Group A); Day 0, Day 7, Day 21(Group B)
CD4⁺/CD8⁺ T-cell ratio (Group A: Day 0, Day 5, Day 14; Group B: Day 0, Day 7, Day 21)
The ratio of CD4⁺ to CD8⁺ T cells will be calculated at all three time points in Group A and Group B.
Measured: Day 0, Day 5, Day 14 (Group A); Day 0, Day 7, Day 21(Group B)
Occurrence of AEs (within 28 days post-vaccinatio)
Adverse events occurring within 28 days of vaccination will be recorded, including solicited local and systemic reactions.
Measured: Within 28 days post-vaccination
Occurrence of SAEs (within 28 days post-vaccination)
Serious adverse events occurring within 28 days of vaccination will be recorded.
Measured: Within 28 days post-vaccination
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted2 Oct 2026
- Study start10 Oct 2026
- Primary completion30 Nov 2026 (estimated)
- Study completion11 Oct 2027 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for InfluenzaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Prevention
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 138 participants (estimated)
Sponsor and investigators
- Lead sponsor
- Ab&B Bio-tech Co., Ltd.JS
- Sponsor type
- University, hospital or other
- Collaborators
- Zhejiang Provincial Center for Disease Control and Prevention, Shangyu District Center for Disease Control and Prevention
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07854392
- Sponsor's protocol ID
- K-2026-070-01
- Status last verified
- Oct 2026
- First submitted
- 27 Sep 2026
- Last updated
- 16 Oct 2026
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- No
- FDA-regulated device
- No