Human Infection Study of H3N2 Influenza in Healthy Adults

NCT06972810 | Completed DMC

• 1 other identifier: 27338
• Study Type: interventional
• Target: 11
• Locations: 1 country
• Sites: 1

Brief Summary

This study will examine how the immune system responds to a flu virus (H3N2) during and after infection in health adults aged between 18 and 50 while in an inpatient facility. The study uses a specific flu virus called the H3N2 influenza challenge virus, that was produced specifically for use in clinical research in controlled conditions. From a previous study, mild to moderate symptoms are expected. This is the first time that a flu challenge study has been undertaken in Australia.

Conditions

Influenza

Keywords

Influenza virus type A (H3N2); Challenge

Outcome Measures

Primary Outcomes (2)

• Percentage of participants who become infected with the virus

  Confirmation of the challenge dose of virus to achieve a symptomatic influenza attack rate (AR) of 78% defined as: Percentage of participants with detectable shedding in nasopharyngeal (NP) swab(s) identified on RT-PCR over any 2 days between days 1-7 post challenge. AND Symptom score that meets the clinical case definition for symptomatic infection (modified Jackson score ≥ 6).

  Day 1 to Day 7 post challenge

• Safety of the H3N2 challenge model

  Frequency and severity of adverse events (AEs) events, either self-reported, or observations, during inpatient confinement and at clinic visits throughout the study period.

  Day 0 to 6 months post challenge

Secondary Outcomes (2)

• Detection of asymptomatic infection

  Day 1 to 7 post challenge

• Percentage of participants who develop influenza antibodies

  Day 0 - 14 post challenge

Other Outcomes (3)

• Investigate associations between virus shedding, symptoms and immune responses of participant post virus inoculation

  Day -2 (baseline) to Day 56

• Investigate associations between virus shedding and immune response kinetics and changes in the microbiome

  Day -2 (baseline) to Day 56

• Determine whether influenza virus is shed into the air following challenge infection

  Day 2 to Day 6 post challenge

Study Arms (1)

Influenza Challenge Model with Influenza A H3N2 virus strain

EXPERIMENTAL

Other: A/Texas/71/2017, clade 3C3a H3N2 influenza virus

Interventions

A/Texas/71/2017, clade 3C3a H3N2 influenza virus OTHER

The intervention product is a live challenge virus that is manufactured in the USA under Good Manufacturing Practice (GMP). The challenge will be administered intranasally using a sprayer device. Participants will be admitted into an inpatient facility prior to the administration of the flu virus. Following inoculation, they will be quarantined for a minimum of 8 days prior to discharge. Participants will receive supportive care and PCR positive participants will receive an effective antiviral medication. Participants will be followed for a total of 6 months.

Also known as: A/Texas/71/2017, clade 3C3a H3N2

Influenza Challenge Model with Influenza A H3N2 virus strain

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• General good health, without significant medical conditions that would interfere with participant safety, as defined by medical history, physical examination, screening laboratory tests, and ECG at a screening evaluation.
• Susceptible to the challenge virus as determined by a baseline serum HAI and NAI antibody titer to the RG-A/Texas/71/2017 (H3N2; clade 3c3a) virus of 1:40 or less.
• Able to understand and comply with planned study procedures and available for the duration of the trial.
• Willing to participate in the study and adhere to all trial requirements, including providing written consent to remain at the trial site for at least seven days after administration of the challenge virus. This willingness must be demonstrated by signing the informed consent document.
• Willing to allow the investigators to discuss the participant's medical history with their General Practitioner or any relevant health professional.
• Willing to refrain from donating blood for the duration of the study period.
• Willing to refrain from smoking and illicit drug use during the quarantine period.
• Women of childbearing potential (WOCBP)\* are required to practice a highly effective form of contraception during the course of the study. Acceptable forms of contraception for female participants include:
• Established use of oral, injected or implanted hormonal methods of contraception (established for a minimum of 4 weeks prior to first inpatient quarantine).
• Placement of an intrauterine device (IUD) or intrauterine system (IUS).
• Male sterilization, if the vasectomized partner is the sole partner for the participant and appropriate post vasectomy documentation of sterilization success is available.
• Same sex intercourse only.
• True abstinence from heterosexual intercourse, when this is in line with the preferred and usual lifestyle of the participant (Periodic abstinence and withdrawal are not acceptable methods of contraception). Careful history and documentation regarding the reliability of this method must be recorded.

You may not qualify if:

• History of clinically significant or currently active neurological, cardiac, respiratory, hepatic, rheumatological, autoimmune, or renal disease. Specifically:
• History of chronic obstructive pulmonary disease, pulmonary hypertension, or chronic lung condition of any etiology;
• Current diagnosis of asthma or reactive airway disease (e.g., to viral infections) within the past 2 years;
• History of thromboembolic, cardiovascular or cerebrovascular disease;
• Current diabetes mellitus (Type I or Type II);
• Any history of malignancy except for non-recurrent basal cell carcinoma;
• History or evidence of clinically significant autoimmune disease or known immunodeficiency of any cause (including HIV);
• History of a surgical splenectomy;
• History of severe psychiatric illness at any time (e.g., psychiatric illness that resulted in inpatient admission, psychosis, suicide attempt) or current significant active symptoms of anxiety and/or depression; i. Participants with history of anxiety-related symptoms of any severity within the last 2 years if the Generalized Anxiety Disorder-7 score is ≥5 ii. Participants with a history of depression of any severity within the last 2 years if the Patient Health Questionnaire-9 score is ≥4
• Bleeding disorder (e.g., factor deficiency, coagulopathy or platelet disorder), or prior history of significant bleeding or bruising following injections or venepuncture; OR
• Other conditions that, in the opinion of the Investigator, could interfere with a participant completing the study and necessary investigations.
• Any clinical laboratory test parameters ≥ 1.5x upper limit of normal (ULN) unless deemed by the investigator to have no clinical significance.
• Body Mass Index (BMI) of less than 18.5 or greater than 32.
• Behavioral or cognitive impairment that in the opinion of the investigator affects the ability of the participant to understand and cooperate with the study protocol.
• The use of alcohol or psychoactive drugs/controlled substances in the past 12 months that:

Sponsors & Collaborators

• National Institute of Allergy and Infectious Diseases (NIAID): collaborator
• University of Melbourne: lead
• WHO Collaborating Centre for Reference and Research on Influenza: collaborator

Study Sites (1)

Doherty Clinical Trials

Melbourne, Victoria, 3002, Australia

Location

MeSH Terms

Conditions

Influenza, Human

Condition Hierarchy (Ancestors)

Respiratory Tract Infections; Infections; Orthomyxoviridae Infections; RNA Virus Infections; Virus Diseases; Respiratory Tract Diseases

Study Officials

• Dr Gail Cross, MBSS (BSc), FRACP

  University of Melbourne

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: NA
• Masking: NONE
• Purpose: BASIC SCIENCE
• Intervention Model: SINGLE GROUP
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Study Record Dates

• First Submitted: April 27, 2025
• First Posted: May 15, 2025
• Study Start: May 5, 2025
• Primary Completion: November 26, 2025
• Study Completion: November 26, 2025
• Last Updated: April 30, 2026

Record last verified: 2025-06

Locations

AU (1)