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Updated May 2026 · ClinicalTrials.gov

RECRUITINGPhase 1 / Phase 2INTERVENTIONAL

Clinical Trials of Quadrivalent Influenza Vaccine

A Randomized, Blinded Phase I./II Clinical Trial to Evaluate the Safety, Tolerability, and Immunogenicity of Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant

Clinical Trials of Quadrivalent Influenza Vaccine (NCT06824519) is a Phase 1 / Phase 2 interventional studying Influenza, Human, sponsored by Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. RECRUITING as of the most recent ClinicalTrials.gov update. Talk to your doctor before contacting the trial site.

Important: This information is not medical advice. Talk to your doctor about whether a clinical trial is right for you.

About This Trial

This clinical trial adopts a seamless design of phase I/II, conducted in two stages: phase I and phase II. Phase I is the age/dose ramp up stage, and phase II is the dose expansion stage.The purpose of this clinical trial is to evaluate the safety and tolerability of different doses of Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant,explore the immunogenicity of the vaccine, and determine the appropriate dose for later clinical trials of this product.

What Stage of Research Is This?

Phase 1 trials test a new treatment for the first time in humans, focusing on safety, dosing, and how the body processes the drug. For Influenza, Human, a Phase 1 study typically enrolls a small number of participants — often healthy volunteers or patients who have exhausted standard treatment options. Phase 1 results determine whether a treatment moves into larger Phase 2 efficacy studies.

This trial is currently recruiting participants. The sponsor has registered the study with ClinicalTrials.gov as actively enrolling, which means new applicants who meet the eligibility criteria can be considered for screening. Trial status can change between updates — confirm current recruiting status with the study contact before traveling for a screening visit.

A target enrollment of 620 participants makes this a sizable late-stage trial. Studies in this range typically have enough power to detect clinically meaningful differences from a comparator and to characterize less-common side effects.

Who May Be Eligible (Plain English)

Who May Qualify: 1. When signing the willing to sign a consent form form, be at least 18 years old and provide valid identification; 2. The subject is able to understand the procedures and methods of this clinical trial, has given sufficient willing to sign a consent form, voluntarily participated, and signed an willing to sign a consent form form by the subject themselves; 3. On the day of enrollment, axillary temperature was ≤ 37.0 ℃; 4. Female and male participants of childbearing age: agree to take effective contraceptive measures within 6 months after vaccination. Who Should NOT Join This Trial: 1. The laboratory test indicators specified in the protocol are abnormal and clinically significant before vaccination (only for Phase I); 2. Have contracted influenza within the past 6 months prior to enrollment (confirmed by any clinical or microbiological method); 3. Previously or currently suffering from autoimmune or weakened immune system diseases; 4. Previous history of severe allergies to any vaccine/drug or any component of the experimental vaccine, such as anaphylactic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, respiratory distress, angioneurotic edema, or individuals with an allergic constitution (such as allergies to two or more drugs, food, or pollen); History of severe allergy to eggs or egg protein; 5. Have received any influenza vaccine within the 6 months prior to enrollment, or plan to receive influenza vaccine other than the vaccine used in this trial during the trial period (before completing the immunization and collecting blood samples); 6. Within 30 days prior to enrollment, any investigational or unregistered products (drugs, vaccines, or devices) have been used, or are planned to be used during the trial period (except for the vaccine used in this trial) (before completing the immunization and collecting blood samples); ...See full criteria on ClinicalTrials.gov Always talk to your doctor about whether this trial is right for you.

These are translations of the protocol\'s inclusion and exclusion criteria, simplified for patients and caregivers. The original clinical text appears below. Eligibility is ultimately confirmed by the trial site\'s screening process — this summary is a starting point for a conversation with your doctor, not a final determination.

Original Eligibility Criteria

View original clinical language
Inclusion Criteria: 1. When signing the informed consent form, be at least 18 years old and provide valid identification; 2. The subject is able to understand the procedures and methods of this clinical trial, has given sufficient informed consent, voluntarily participated, and signed an informed consent form by the subject themselves; 3. On the day of enrollment, axillary temperature was ≤ 37.0 ℃; 4. Female and male participants of childbearing age: agree to take effective contraceptive measures within 6 months after vaccination. Exclusion Criteria: 1. The laboratory test indicators specified in the protocol are abnormal and clinically significant before vaccination (only for Phase I); 2. Have contracted influenza within the past 6 months prior to enrollment (confirmed by any clinical or microbiological method); 3. Previously or currently suffering from autoimmune or immunodeficiency diseases; 4. Previous history of severe allergies to any vaccine/drug or any component of the experimental vaccine, such as anaphylactic shock, allergic laryngeal edema, allergic purpura, thrombocytopenic purpura, respiratory distress, angioneurotic edema, or individuals with an allergic constitution (such as allergies to two or more drugs, food, or pollen); History of severe allergy to eggs or egg protein; 5. Have received any influenza vaccine within the 6 months prior to enrollment, or plan to receive influenza vaccine other than the vaccine used in this trial during the trial period (before completing the immunization and collecting blood samples); 6. Within 30 days prior to enrollment, any investigational or unregistered products (drugs, vaccines, or devices) have been used, or are planned to be used during the trial period (except for the vaccine used in this trial) (before completing the immunization and collecting blood samples); 7. The interval between receiving attenuated live vaccines before enrollment is less than 30 days, and the interval between receiving other non live vaccines is less than 14 days; 8. Within the first 3 days of enrollment, have experienced acute illness or are in the acute phase of chronic illness; 9. Used antipyretic, analgesic, or anti allergic drugs within 3 days prior to enrollment; 10. Use immunoglobulin and/or any blood products within 3 months prior to enrollment, or plan to use them during the trial period (before completing immunization and collecting blood samples); 11. Long term use of immunosuppressants or other immunomodulatory drugs (defined as continuous use for more than 14 days) within the first 3 months of enrollment, such as a glucocorticoid dose of ≥ 0.5 mg/kg/day (inhalation and local steroid hormones are not restricted); 12. Absence of spleen, functional absence of spleen, and splenectomy caused by any condition; 13. Any obvious coagulation dysfunction or history of anticoagulant therapy; 14. History of epilepsy, encephalopathy, and malignant tumors; 15. Suffering from serious cardiovascular system diseases, serious hypertension with unstable drugs (systolic pressure ≥ 160mmHg and/or diastolic pressure ≥ 100mmHg), diabetes with serious complications and other serious chronic diseases; 16. Currently suffering from respiratory system diseases (including pneumonia, tuberculosis, severe asthma, chronic bronchitis, etc.), acute liver and kidney diseases (severe impairment of liver and kidney function), mental disorders (such as schizophrenia, depression, affective disorders, etc.), etc; 17. Women of childbearing age who are breastfeeding, pregnant, or have a positive urine pregnancy test before enrollment; 18. Plan to move out of the local area before the end of the study or plan to leave the local area for a long time during the study visit; 19. According to the researchers' judgment, the subjects have any other factors that are not suitable for participating in the clinical trial.

Treatments Being Tested

BIOLOGICAL

Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant (low dose)

Inject 1 dose of low-dose vaccine

BIOLOGICAL

Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant placebo (low dose)

Inject 1 dose of low-dose placebo

BIOLOGICAL

Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant (high dose)

Inject 1 dose of high-dose vaccine

BIOLOGICAL

Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant placebo (high dose)

Inject 1 dose of high-dose placebo

BIOLOGICAL

Influenza Vaccine (Split Virion), Inactivated, Quadrivalent

Inject 1 dose of positive control vaccine

Locations (1)

Trial sites listed on ClinicalTrials.gov for this study. Site activation status can vary — confirm with the specific site before traveling for a screening visit.

Hebei Province Centers for Disease Control and Prevention
Shijiazhuang, Hebei, China

How to Talk to Your Doctor About This Trial

Bring the printable summary of this trial — including the NCT ID (NCT06824519), the sponsor (Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.), and the key eligibility criteria — to your next appointment. Your doctor can review the inclusion and exclusion criteria against your medical history, lab values, and current treatments to assess whether you are likely to qualify. They can also help you weigh whether trial participation makes sense alongside your existing care plan.

Useful questions to walk through together: What does the trial protocol require beyond standard care? How long is the active treatment phase, and how long is follow-up? Are there study visits at sites I can reach? Who pays for the trial-specific procedures, and who pays for standard-of-care portions? See our 25 questions to ask about clinical trials guide for a more complete checklist.

Authoritative Sources

The official record for this trial lives on ClinicalTrials.gov — the federal registry maintained by the National Library of Medicine at NIH. For background on how this trial fits into the FDA approval pathway, see the FDA drug approval process. For oncology-specific guidance for patients considering trials, the National Cancer Institute publishes patient-oriented overviews. International trial registries are aggregated by the WHO ICTRP.

Frequently Asked Questions

What is the NCT06824519 clinical trial studying?

This clinical trial adopts a seamless design of phase I/II, conducted in two stages: phase I and phase II. Phase I is the age/dose ramp up stage, and phase II is the dose expansion stage.The purpose of this clinical trial is to evaluate the safety and tolerability of different doses of Influenza Vaccine (Split Virion), Inactivated, Quadrivalent, ZFA02 Adjuvant,explore the immunogenicity of the vaccine, and determine the appropriate dose for later clinical trials of this product. The full protocol is registered on ClinicalTrials.gov and includes the primary outcome measures, eligibility criteria, and study endpoints.

Who can participate in NCT06824519?

Eligibility for this trial depends on the specific inclusion and exclusion criteria set by the sponsor. The plain-English summary above translates the most important criteria into accessible language; the official clinical text is preserved in the collapsible section underneath. Whether you fit any specific trial is a medical decision your doctor needs to confirm — bring the trial information to your treating physician for a full review against your medical history.

How do I contact the trial site for NCT06824519?

Contact information registered with ClinicalTrials.gov is shown in the sidebar of this page. Before reaching out, confirm with your treating physician that this trial is appropriate for your situation. The trial site will then walk you through the screening process to determine final eligibility.

Is participating in a clinical trial safe?

Clinical trials in the United States are regulated by the FDA and overseen by Institutional Review Boards (IRBs) that review the protocol for safety. Risk varies by trial — Phase 1 studies test new treatments in humans for the first time, while Phase 3 trials use treatments that have already passed earlier safety screening. The informed consent document for any specific trial details the known risks and what to expect. Discuss those risks with your physician before deciding whether to participate.

Where can I verify the data on this page?

Every detail on this page comes directly from the ClinicalTrials.gov API. Click "View on ClinicalTrials.gov" in the sidebar to see the official, unmodified record. The federal record is always authoritative; this page is a structured presentation with a plain-English eligibility translation. For background on how clinical trials are regulated, see the FDA drug approval process documentation.

How This Page Is Built

Every field on this page is pulled directly from the ClinicalTrials.gov API v2 — no estimates, no proxies. The plain-English eligibility translation is generated from the original protocol text and reviewed for fidelity to the underlying clinical criteria. The original clinical text remains visible in the collapsible section above so users and clinicians can verify the translation. Read the full methodology for the data pipeline and known limitations.

Source: ClinicalTrials.gov API v2 record for NCT06824519. Maintained by the National Library of Medicine at NIH. Public domain. Cite as: "TrialFinderData. NCT06824519. Data: ClinicalTrials.gov."

Medical disclaimer: This page is informational, not medical advice. Talk to your doctor about whether a clinical trial is right for you.

Last updated 2026-05-08 · Data from ClinicalTrials.gov.