Healthy ParticipantsPhase 2NCT06481579

A Study of IVX-A12 in Adults Participants

A Phase 2 study testing IVX-A12 and Licensed RSV Vaccine in people with Healthy Participants, run by Icosavax, Inc. at 5 sites in United States.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Official record

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Trial summary

The primary purpose of this study is to assess the immunogenicity and safety of IVX-A12 in adults 60 years of age and older. Read more about this study

Who is it for?: Ages 60 years and olderHealthy volunteers can take part
Conditions the study is for: Healthy Participants
What is being tested?: IVX-A12 and Licensed RSV Vaccine
Type of treatment: Vaccines, Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 143 participants
Where: 5 sitesUnited States
Study dates: 10 Jun 2024to 19 Dec 2024
Phase: Phase 2
Are there results?: Yes, posted in the registrySummary in the doctors' view

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 60 years and older
All sexes
Healthy volunteers accepted
Adult, Older adult

Who may be able to join

Adults >=60 years of age at the time of signing informed consent.
Participants who are medically stable according to the judgment of the Investigator.
Able to understand and comply with study requirements/procedures based on the assessment of the Investigator.
Capable of giving signed informed consent.

Who cannot join

Acute (time-limited) or febrile (temperature >=38.0 °C [100.4 ºF]) illness/infection within 3 days of planned dosing.
History of a clinically significant bleeding disorder (e.g., factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venipuncture.
History of hypersensitivity to any component of the study vaccination.
History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (e.g., anaphylaxis).
Known or suspected congenital or acquired immunodeficiency.
Known or suspected autoimmune condition as determined by history and/or physical examination.

Show all 18Show fewer

History of Guillain-Barré syndrome or any other demyelinating condition.
History of malignancy other than treated non-melanoma skin cancers or locally-treated cervical cancer in previous 5 years.
Any condition that may significantly increase the risk to the participant because of participation in the study, impact the participant's ability to participate in the study, or impair the interpretation of the study data.
Receipt of any licensed or investigational RSV and/or Human metapneumovirus (hMPV) vaccine any time prior to administration of study intervention.
Receipt of any licensed vaccine (other than licensed influenza or COVID-19 vaccines) within 28 days prior to or expected receipt within 28 days after administration of study intervention. Licensed influenza or COVID-19 vaccines are permitted beginning greater than (>)14 days prior to and >14 days after administration of study intervention.
Receipt of immunoglobulin or blood products within 3 months prior to administration of study intervention or expected receipt during the study.
Receipt of immune-modifying drugs or immunosuppressive therapy, such as anti-cancer chemotherapy or radiation therapy within 6 months prior to enrollment (or expected receipt during study), or long-term systemic corticosteroid therapy (prednisolone or equivalent at a dose of >=20 mg daily or every other day for more than 2 consecutive weeks) within 6 months prior to study intervention or anticipated receipt during study.
Participation in another study or receiving interventional study investigational medicinal product (IMP), in the preceding 28 days or expected receipt of another study intervention (or participation in another study) during the period of study follow-up.
Employees of the Sponsor involved in planning, executing, supervising, or reviewing the IVX-A12 program, clinical study site staff, or any other individuals involved with the conduct of the study, or immediate family members of such individuals.
Alcohol or substance abuse that, in the opinion of the Investigator, might interfere with the study conduct or completion.
Deprived of freedom by an administrative or court order, or in emergency setting, or hospitalized involuntarily.
Judgment by the Investigator that the participant should not participate in the study if the participant is unlikely to comply with study procedures, restrictions, and requirements.

Trial locations and contacts

5 sites in 1 country.

City, postcode or hospital

5 sites in 1 country

United States5 sites

Icosavax Investigational Site US022
Anaheim, California, 92801
Icosavax Investigational Site US002
Hollywood, Florida, 33024
Icosavax Investigational Site US011
Lenexa, Kansas, 66219
Icosavax Investigational Site US016
North Charleston, South Carolina, 29405
Icosavax Investigational Site US021
Rolling Hills Estates, California, 90274

Other trials in United States

About this study

Official title: A Phase 2, Randomized, Modified Double-Blind, Active Controlled Study to Characterize the Safety and Immunogenicity of IVX-A12 in Adults 60 Years of Age and Older

The primary purpose of this study is to assess the immunogenicity and safety of IVX-A12 in adults 60 years of age and older.

Read the detailed description

This is a randomized, modified double-blind, active controlled study to characterize the immunogenicity and safety of IVX-A12.

Approximately 140 participants will be randomized in a 1:1 ratio to receive IVX-A12 (approximately 70) or licensed respiratory syncytial virus (RSV) vaccine (AREXVY) (approximately 70).

The study is planned to be conducted at approximately 5 sites in the United States. The duration of each participant's involvement in the study will be approximately 6 months following administration of study vaccination.

Conditions: Healthy Participants
Being tested: IVX-A12, Licensed RSV Vaccine
Keywords: Respiratory syncytial virus (RSV), Human metapneumovirus (hMPV)

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

IVX-A12Biological
IVX-A12 IM injection.
Licensed RSV VaccineBiological
Also called AREXVY
Licensed RSV Vaccine (AREXVY) IM injection.

Study groups in NCT06481579
Study group	Role	What they receive
IVX-A12 Vaccine	Experimental	Participants will receive a single dose of IVX-A12, 300 micrograms (mcg), intramuscular (IM) injection on Day 1. Receives: Biological: IVX-A12
Licensed RSV Vaccine	Active comparator	Participants will receive a single dose of licensed RSV vaccine (AREXVY) IM injection on Day 1. Receives: Biological: Licensed RSV Vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

Model-adjusted Geometric Mean Concentration (GMC) for RSV/A Neutralizing Antibodies (NAb)
Model-adjusted GMCs and 95% CIs were derived using an ANCOVA model for log2 nAb responses at Day 29 with independent variables of study intervention, log2 baseline response, and age group. Measured values were calculated as the anti-logarithm transformation of the least square means and 95% CIs from the model.
Measured: At Day 29
Geometric Mean Fold Rise (GMFR) in RSV/A NAb Concentrations
The GMFR was calculated as the anti-logarithm of Σ(log2 transformed (post-baseline response/baseline response)/n), where n is the number of participants with non-missing response information at baseline and at the post-baseline timepoint.
Measured: From baseline up to Day 29
Number of Participants With Immediate Unsolicited Adverse Events (AEs)
Immediate AEs were defined as having an onset time within 30 minutes after study vaccination.
Measured: Within the 30 minutes after vaccination on Day 1
Number of Participants With Injection Site and Systemic Solicited Adverse Reactions (ARs)
The injection site solicited ARs included predefined injection site pain, injection site erythema/redness, and injection site swelling. The systemic solicited ARs included predefined fever, chills, headache, myalgia (muscle aches and pains), and fatigue (physical or mental tiredness).
Measured: Day 1 through Day 8
Number of Participants With Unsolicited Adverse Events (AEs)
The unsolicited AEs were any AE other than predefined solicited AEs.
Measured: Day 1 through Day 29
Number of Participants With Serious Adverse Events (SAEs), Medically-attended Adverse Events (MAAEs), and Adverse Events of Special Interests (AESIs)
A SAE defined as an AE that occurred during any phase of study and met one or more of following criteria: resulted in death; was immediately life-threatening; required in-patient hospitalization or led to prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; was a congenital anomaly or birth defect; or was considered an important medical event that might have jeopardized the participant or required medical intervention to prevent one of aforementioned outcomes. MAAEs defined as AEs leading to medically-attended visits that were not routine visits for physical examination or vaccination, such as an emergency room visit, or an otherwise unscheduled visit to or from medical personnel (medical doctor) for any reason. An AESI was an event of scientific and medical interest, specific to further understanding of safety profile of investigational vaccine and required close monitoring and rapid communication by Investigators to the Sponsor.
Measured: Day 1 through Day 29

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

10 Jun 202419 Dec 2024

First posted1 Jul 2024
Study start10 Jun 2024
Primary completion17 Jul 2024
Study completion19 Dec 2024

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Posted resultsParticipant flow, outcome measures and adverse events reported by the sponsor.
Other trials for Healthy ParticipantsStudies 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 2
Primary purpose: Other
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind
Who is masked: Participant, Investigator, Outcomes assessor
Enrolment: 143 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06481579
Sponsor's protocol ID: ICVX-12-202
Status last verified: Jul 2025
First submitted: 25 Jun 2024
Last updated: 26 Aug 2025
Results posted: Yes, on ClinicalTrials.gov
Data monitoring committee: No
FDA-regulated drug: Yes
FDA-regulated device: No
Individual data sharing: No

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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Study at a glance

From the registry record, last updated by the sponsor on 26 Aug 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: A Phase 2, Randomized, Modified Double-Blind, Active Controlled Study to Characterize the Safety and Immunogenicity of IVX-A12 in Adults 60 Years of Age and Older
ClinicalTrials.gov ID: NCT06481579
Acronym / sponsor ID: ICVX-12-202
Conditions: Healthy Participants
Keywords: Respiratory syncytial virus (RSV), Human metapneumovirus (hMPV)
Phase: Phase 2
Study type: Interventional
Recruitment status: Completed
Enrolment: 143 participants (actual)
Lead sponsor: Icosavax, Inc.Industry (pharma, biotech, devices)
Study start: 10 Jun 2024 (actual)
Primary completion: 17 Jul 2024 (actual)
Study completion: 19 Dec 2024 (actual)
First posted: 1 Jul 2024 (actual)
Results: Posted 26 Aug 2025

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

The primary purpose of this study is to assess the immunogenicity and safety of IVX-A12 in adults 60 years of age and older.

Detailed description

This is a randomized, modified double-blind, active controlled study to characterize the immunogenicity and safety of IVX-A12.

Approximately 140 participants will be randomized in a 1:1 ratio to receive IVX-A12 (approximately 70) or licensed respiratory syncytial virus (RSV) vaccine (AREXVY) (approximately 70).

Study design

Primary purpose: Other
Allocation: Randomised
Intervention model: Parallel groups
Masking: Triple blind (participant, investigator, outcomes assessor)
Number of arms: 2

Arm	Type	Receives
IVX-A12 Vaccine	Experimental	Biological: IVX-A12Participants will receive a single dose of IVX-A12, 300 micrograms (mcg), intramuscular (IM) injection on Day 1.
Licensed RSV Vaccine	Active comparator	Biological: Licensed RSV VaccineParticipants will receive a single dose of licensed RSV vaccine (AREXVY) IM injection on Day 1.

Who may qualify

Ages: 60 years and older
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (4 listed)

Adults >=60 years of age at the time of signing informed consent.
Participants who are medically stable according to the judgment of the Investigator.
Able to understand and comply with study requirements/procedures based on the assessment of the Investigator.
Capable of giving signed informed consent.

Key exclusion criteria (18 listed)

Acute (time-limited) or febrile (temperature >=38.0 °C [100.4 ºF]) illness/infection within 3 days of planned dosing.
History of a clinically significant bleeding disorder (e.g., factor deficiency, coagulopathy, or platelet disorder), or prior history of significant bleeding or bruising following IM injections or venipuncture.
History of hypersensitivity to any component of the study vaccination.
History of severe adverse reaction associated with a vaccine and/or severe allergic reaction (e.g., anaphylaxis).
Known or suspected congenital or acquired immunodeficiency.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
IVX-A12IVX-A12 IM injection.	Biological	IVX-A12 Vaccine
Licensed RSV VaccineAlso: AREXVYLicensed RSV Vaccine (AREXVY) IM injection.	Biological	Licensed RSV Vaccine

Primary outcome

Model-adjusted Geometric Mean Concentration (GMC) for RSV/A Neutralizing Antibodies (NAb)
Time frame: At Day 29
Model-adjusted GMCs and 95% CIs were derived using an ANCOVA model for log2 nAb responses at Day 29 with independent variables of study intervention, log2 baseline response, and age group. Measured values were calculated as the anti-logarithm transformation of the least square means and 95% CIs from the model.
Geometric Mean Fold Rise (GMFR) in RSV/A NAb Concentrations
Time frame: From baseline up to Day 29
The GMFR was calculated as the anti-logarithm of Σ(log2 transformed (post-baseline response/baseline response)/n), where n is the number of participants with non-missing response information at baseline and at the post-baseline timepoint.
Number of Participants With Immediate Unsolicited Adverse Events (AEs)
Time frame: Within the 30 minutes after vaccination on Day 1
Immediate AEs were defined as having an onset time within 30 minutes after study vaccination.
Number of Participants With Injection Site and Systemic Solicited Adverse Reactions (ARs)
Time frame: Day 1 through Day 8
The injection site solicited ARs included predefined injection site pain, injection site erythema/redness, and injection site swelling. The systemic solicited ARs included predefined fever, chills, headache, myalgia (muscle aches and pains), and fatigue (physical or mental tiredness).
Number of Participants With Unsolicited Adverse Events (AEs)
Time frame: Day 1 through Day 29
The unsolicited AEs were any AE other than predefined solicited AEs.
Number of Participants With Serious Adverse Events (SAEs), Medically-attended Adverse Events (MAAEs), and Adverse Events of Special Interests (AESIs)
Time frame: Day 1 through Day 29
A SAE defined as an AE that occurred during any phase of study and met one or more of following criteria: resulted in death; was immediately life-threatening; required in-patient hospitalization or led to prolongation of existing hospitalization; resulted in persistent or significant disability or incapacity; was a congenital anomaly or birth defect; or was considered an important medical event that might have jeopardized the participant or required medical intervention to prevent one of aforementioned outcomes. MAAEs defined as AEs leading to medically-attended visits that were not routine visits for physical examination or vaccination, such as an emergency room visit, or an otherwise unscheduled visit to or from medical personnel (medical doctor) for any reason. An AESI was an event of scientific and medical interest, specific to further understanding of safety profile of investigational vaccine and required close monitoring and rapid communication by Investigators to the Sponsor.

Results and safety

Results posted to the registry on 26 Aug 2025, as reported by the sponsor. Figures are copied from the record, not re-analysed. Full results on ClinicalTrials.gov.

Participant flow

Group	Started	Completed
IVX-A12	71	66
AREXVY	72	71

Primary outcome: Model-adjusted Geometric Mean Concentration (GMC) for RSV/A Neutralizing Antibodies (NAb)

Time frame: At Day 29. Geometric mean (95% Confidence Interval). Unit: internation unit per milliliter (IU/mL)

Measure	IVX-A12 n = 66	AREXVY n = 67
Value	5910.4 (4210.4 to 8296.8)	10500.4 (7565.2 to 14574.3)

Population analysed: Immunogenicity analysis set (IAS) included all participants in the SAF who had no eligibility-related protocol deviations judged to have the potential to interfere with the generation or interpretation of an immune response. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure.

Primary outcome: Geometric Mean Fold Rise (GMFR) in RSV/A NAb Concentrations

Time frame: From baseline up to Day 29. Geometric mean (95% Confidence Interval). Unit: fold rise

Measure	IVX-A12 n = 66	AREXVY n = 67
Value	3.4 (2.7 to 4.3)	6.5 (5.0 to 8.5)

Population analysed: IAS included all participants in the SAF who had no eligibility-related protocol deviations judged to have the potential to interfere with the generation or interpretation of an immune response. Here, "Overall Number of Participants Analyzed" signifies participants who were evaluable for this outcome measure.

Primary outcome: Number of Participants With Immediate Unsolicited Adverse Events (AEs)

Time frame: Within the 30 minutes after vaccination on Day 1. Count of participants. Unit: Participants

Measure	IVX-A12 n = 71	AREXVY n = 72
Value	0	0

Population analysed: The SAF included all randomized participants who received one dose of study intervention, irrespective of their protocol adherence and continued participation in the study.

Primary outcome: Number of Participants With Injection Site and Systemic Solicited Adverse Reactions (ARs)

Time frame: Day 1 through Day 8. Count of participants. Unit: Participants

Measure	IVX-A12 n = 71	AREXVY n = 72
Solicited injection site AR	14	31
Solicited systemic AR	19	17

Population analysed: The SAF included all randomized participants who received one dose of study intervention, irrespective of their protocol adherence and continued participation in the study.

Adverse events

Time frame: Day 1 through Day 181. Other adverse events reported at 0% frequency or more

Group	Serious adverse events	Other adverse events	Deaths
IVX-A12	2 of 71 (2.8%)	6 of 71 (8.5%)	1 of 71
AREXVY	1 of 72 (1.4%)	15 of 72 (20.8%)	0 of 72

Loading the posted results from ClinicalTrials.gov…

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 26 Aug 2025.
Posted resultsParticipant flow, baseline, all outcome measures and adverse events.
Individual participant dataSharing planned: No

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

The record lists no contact. Use the official record to reach the sponsor.

5 sites in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 2 study testing IVX-A12 and Licensed RSV Vaccine in people with Healthy Participants, run by Icosavax, Inc. at 5 sites in United States.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 18 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 26 Aug 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 5 sites in United States. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 2 studies give the treatment to a larger group to see whether it has the intended effect and to keep checking safety.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

Yes. Results are posted in the registry (first posted 26 Aug 2025). A summary is in the For doctors view, and the full results are on ClinicalTrials.gov.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Model-adjusted Geometric Mean Concentration (GMC) for RSV/A Neutralizing Antibodies (NAb) (time frame: At Day 29). The study lists 6 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06481579.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 26 Aug 2025.