COVID-19Phase 1NCT07095231
Safety, Reactogenicity, and Immunogenicity Trial of STX-S SARS-CoV-2 Vaccine in Adults
A Phase 1 study testing STX-S in people with COVID-19, run by National Institute of Allergy and Infectious Diseases (NIAID) at 3 sites in United States.
Trial summary
This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. Read more about this study
- Who is it for?
- Ages 18 to 64 yearsHealthy volunteers can take part
- Conditions the study is for
- COVID-19
- What is being tested?
- STX-S
- Type of treatment
- Vaccines, Injection or infusion
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 60 participants
- Where
- 3 sitesUnited States
- Study dates
- 11 Aug 2025to 16 Jun 2026
- Phase
- Phase 1
- Are there results?
- None posted in the registry
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 64 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Provides written informed consent before initiation of any study procedures.
- Able to understand and agree to comply with planned study procedures and be available for all study visits.
- Non-pregnant adults, 18 through 64 years of age at the time of study product administration.
- Participants of childbearing potential* must agree to use or have practiced true abstinence or use at least one acceptable primary form of contraception*
- These criteria apply to females who are in a heterosexual relationship who are of childbearing potential. Not of childbearing potential include post-menopausal females (defined as having a history of amenorrhea for at least one year) or a documented status as being surgically sterile (hysterectomy, bilateral oophorectomy, or tubal ligation/salpingectomy).
- True abstinence is 100% of the time, no sexual intercourse (penis enters the vagina). Periodic abstinence [e.g., calendar, ovulation, symptothermal, post-ovulation methods] and withdrawal are not acceptable methods.
Show all 15Show fewer
- Acceptable forms of primary contraception include a monogamous relationship with a vasectomized partner who has been vasectomized for 180 days or more before the participant's study product administration, intrauterine devices, birth control pills, and injectable/implantable/insertable/transdermal hormonal birth control products. Must have used at least one acceptable primary form of contraception for at least 30 days before study product administration and agree to continue at least one acceptable primary form of contraception through 60 days after study product administration.
- Male participants must use acceptable contraception* or be vasectomized and must refrain from donating sperm for 60 days following study product administration.
- Acceptable contraception includes abstinence from intercourse with a female participant of childbearing potential or use of a male condom. Contraception use does not apply to males in an exclusively same-sex relationship.
- Participants of childbearing potential must have a negative urine pregnancy test at screening and within 24 hours before study product administration.
- In general good health.* *As determined by medical history and physical examination, including vital signs, to evaluate acute or ongoing chronic medical diagnoses/conditions that have been present for at least 90 days, which would affect the assessment of the safety of participants. Chronic medical diagnoses/ conditions should be stable for the last 30 days (i.e., no hospitalizations, emergency room (ER), or urgent care for the condition). This includes no change in chronic prescription medication, dose, or frequency due to deterioration of the chronic medical diagnosis/condition 30 days before the study product administration. Any prescription change, due to a change of health care provider, insurance company, etc., or done for financial reasons and in the same class of medication will not be considered a deviation of this inclusion criterion. Participants may be on chronic or as-needed (prn) medications if, in the opinion of the participating site Principal Investigator or appropriate sub-investigator, they pose no additional risk to participant safety or assessment of reactogenicity and immunogenicity.
- Receipt of a complete primary authorized or approved COVID-19 vaccine series and at least one booster* with the last vaccination at least 16 weeks before study product administration.
- Booster may be either homologous or heterologous to the primary vaccine series. It must be a Food and Drug Administration (FDA)-authorized/licensed vaccine, though doses may have been received during a clinical trial.
- Clinical screening laboratory evaluations are within normal reference ranges or grade 1 with no clinical significance (NCS) per the investigator's discretion.* *(White Blood Cells [WBCs] with differential, hemoglobin [Hgb], platelets [PLTs], Alanine Transaminase [ALT], Aspartate Transaminase [AST], Creatinine [Cr], Alkaline Phosphatase [ALP], Total Bilirubin [T. Bili]). ALT, AST, ALP, T. Bili, and creatinine values below the reference range will not be exclusionary as these values below the reference range are clinically insignificant.
- Must agree to have samples stored for secondary research.
Who cannot join
- Positive SARS-CoV-2 PCR at screening.
- Abnormal vital signs (Grade 1 or higher)*:
- Grade 1 or higher is equivalent to: Systolic blood pressure (SBP) >/= 141 mmHg or </= 89 mmHg Diastolic blood pressure (DBP) >/= 91 mmHg Heart rate (HR) is >/= 101 beats per minute or </= 54 beats per minute Oral temperature >/= 38.0 degrees Celsius (100.4 degrees Fahrenheit)
- History of SARS-CoV-2 infection or receipt of any COVID-19 vaccine < 16 weeks prior to study product administration.
- Participant who is pregnant or breastfeeding.
- Blood or plasma donation within 4 weeks before study product administration.
Show all 31Show fewer
- Receipt of antibody or blood-derived products within 90 days before study product administration.
- Any self-reported or documented significant medical or psychiatric diseases* or any other condition that, in the opinion of the site Principal Investigator (PI) or appropriate sub-investigator, precludes study participation.
- Significant medical or psychiatric conditions include but are not limited to significant kidney disease, liver disease, ongoing malignancy, or recent diagnosis of malignancy in the last five years, excluding treated basal and squamous cell carcinoma of the skin and cervical carcinoma in situ, which are allowed.
- Neurological or neurodevelopmental conditions*
- Including history of Bell's palsy, history of four or more migraine headaches in the past 12 months that interfered with normal daily activity or any migraine headache in the past 5 years that required emergency or inpatient medical care, epilepsy, seizures in the last 5 years, encephalopathy, focal neurologic deficits, Guillain-Barré syndrome, encephalomyelitis, transverse myelitis, stroke or transient ischemic attack, multiple sclerosis, Parkinson's disease, amyotrophic lateral sclerosis, Creutzfeldt-Jakob disease, or Alzheimer's disease.
- History of significant respiratory disease requiring daily medications currently, history of asthma in the past 5 years, or any treatment of respiratory disease exacerbations in the last 5 years.
- History of cardiovascular disease (e.g., congestive heart failure, cardiomyopathy, ischemic heart disease), including any history of myocarditis, pericarditis, or uncontrolled cardiac arrhythmia.
- Any autoimmune disease, including hypothyroidism, without a defined non-autoimmune cause.
- Has an acute illness determined by the site Principal Investigator or appropriate sub-investigator within 72 hours before study product administration*.
- An acute illness that is nearly resolved with only minor residual symptoms remaining is allowable if, in the opinion of the participating site Principal Investigator or appropriate sub-investigator, the residual symptoms will not interfere with the ability to assess safety parameters as required by the protocol.
- Has a positive test result for hepatitis B surface antigen, hepatitis C virus RNA (by reflex testing), or human immunodeficiency virus (HIV) antigen/antibody test at screening.
- Has any confirmed or suspected immunosuppressive or immunodeficient state such as asplenia, recurrent severe infections, and chronic* immunosuppressant medication within the past 6 months.**
- Chronic means more than 14 continuous days.
- Ophthalmic and topical steroids are allowed. See exclusion 19 for intranasal steroids.
- Has received any investigational product within 60 days, or 5 half-lives, whichever is longer, before study product administration or is planning to receive one during the study.
- Has a history of hypersensitivity or severe allergic reaction* to any previous licensed or unlicensed vaccine or the study product components.**
- (e.g., anaphylaxis, generalized urticaria, angioedema, other significant reaction)
- See Investigative Brochure (IB) for study product formulation.
- Received or plans to receive licensed inactivated/subunit vaccine within 14 days of study product administration or live vaccine within 28 days of study product administration.
- Plan to receive a COVID-19 booster vaccine within the 180 days following study product administration.
- Regular use of intranasal medications, including steroids*
- Participants must have had no intranasal medication use for 30 days before study product administration and do not plan to use intranasal medications for 30 days after study product administration for medications other than steroids and for 3 months after study product administration for intranasal steroids (including over-the-counter (OTC) fluticasone).
- Use of intranasal illicit drugs in the 5 years before study product administration or plans to use during the study.
- Current smoker (including cigarettes, marijuana, and vaping) or smoking within the prior 3 months.
- Planned international travel between study product administration and Day 29 visit.
Trial locations and contacts
3 sites in 1 country.
United States3 sites
University of Rochester Medical Center - Vaccine Research Unit
Rochester, New York, 14642-0001
Kaiser Permanente Washington Health Research Institute
Seattle, Washington, 98101-1466
The University of Washington - Virology Research Clinic
Seattle, Washington, 98104
About this study
Official title: A Phase 1 Dose Escalation Study to Assess the Safety, Reactogenicity, and Immunogenicity of STX-S for Prevention of SARS-CoV-2 Infection as a Booster Dose
This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. The study is designed as a non-randomized, open-label, dose-escalation clinical trial evaluating three dose levels of STX-S. A sample size of 60 participants (20 participants per dose cohort) is anticipated. The primary objective is to evaluate the safety and reactogenicity of a single intramuscular injection of three different dose levels (25 ng, 50 ng, and 125 ng) of STX-S in previously vaccinated healthy adults
Read the detailed description
This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. The study is designed as a non-randomized, open-label, dose-escalation clinical trial evaluating three dose levels of STX-S. A sample size of 60 participants (20 participants per dose cohort) is anticipated. The primary objective is to evaluate the safety and reactogenicity of a single intramuscular injection of three different dose levels (25 ng, 50 ng, and 125 ng) of STX-S in previously vaccinated healthy adults. The secondary objectives are to evaluate the systemic anti-Spike humoral immune responses of a single Intramuscular (IM) injection of STX-S and to evaluate nasal mucosal Immunoglobulin A (IgA) and Immunoglobulin G (IgG) responses after study product administration.
- Conditions
- COVID-19
- Being tested
- STX-S
- Keywords
- Booster Dose, Capricor, coronavirus, Dose-Escalation, NextGen, phase 1, STX-S, vaccine
- Medical subject headings
- COVID-19, Coronavirus Infections
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
STX-SBiological
A proprietary vaccine developed internally by Capricor utilizing exosomes that were engineered to express spike proteins on the surface
| Study group | Role | What they receive |
|---|---|---|
| Cohort 1 | Experimental | Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 25 ng at a volume of 0.25 mL. Three sentinel participants, aged < 50, will be enrolled over at least 2 days. The Protocol Safety Review Team (PSRT) will conduct a safety review before enrolling the remainder of the cohort. N=20 Receives: Biological: STX-S |
| Cohort 2 | Experimental | Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 50 ng at a volume of 0.5 mL. N=20 Receives: Biological: STX-S |
| Cohort 3 | Experimental | Healthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 125 ng at a volume of 0.5 mL. N=20 Receives: Biological: STX-S |
What is being measured
The primary outcome is the main question the study is designed to answer.
Occurrence of abnormal clinical safety laboratory adverse events (AEs).
Measured: Through Day 8
Occurrence of adverse events of special interest (AESI)
Measured: Through 6 months post study product administration
Occurrence of medically attended adverse events (MAAEs)
Measured: Through 6 months post study product administration
Occurrence of new onset chronic medical conditions (NOCMCs)
Measured: Through 6 months post study product administration
Occurrence of serious adverse events (SAEs)
Measured: Through 6 months post study product administration
Occurrence of solicited local adverse events (AEs).
Measured: Through Day 7 post study product administration
Occurrence of solicited systemic adverse events (AEs).
Measured: Through Day 7 post study product administration
Occurrence of unsolicited adverse events (AEs).
Measured: Through Day 28 post study product administration
Secondary outcomes (5)
Nasal mucosal anti-spike binding IgA antibodies
Measured: Day 1 through Day 91
Nasal mucosal anti-spike binding IgG antibodies
Measured: Day 1 through Day 91
Serum Anti-spike binding Immunoglobulin A (IgA) antibody
Measured: Day 1 through Day 181
Serum Anti-spike binding Immunoglobulin G (IgG) antibody
Measured: Day 1 through Day 181
Serum Anti-spike neutralizing antibodies
Measured: Day 1 through Day 181
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted31 Jul 2025
- Study start11 Aug 2025
- Primary completion16 Jun 2026
- Study completion16 Jun 2026
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for COVID-19Studies of the same condition, open and under way.
- More trials run by National Institute of Allergy and Infectious Diseases (NIAID)The sponsor's other registered studies.
- 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 1
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Enrolment
- 60 participants (actual)
Sponsor and investigators
- Sponsor type
- US National Institutes of Health
- Responsible party
- Sponsor
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT07095231
- Sponsor's protocol ID
- 24-1104
- Status last verified
- 17 Jul 2025
- First submitted
- 24 Jul 2025
- Last updated
- 26 Jun 2026
- Results posted
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 26 Jun 2026. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- A Phase 1 Dose Escalation Study to Assess the Safety, Reactogenicity, and Immunogenicity of STX-S for Prevention of SARS-CoV-2 Infection as a Booster Dose
- ClinicalTrials.gov ID
- NCT07095231
- Acronym / sponsor ID
- 24-1104
- Conditions
- COVID-19
- Keywords
- Booster Dose, Capricor, coronavirus, Dose-Escalation, NextGen, phase 1, STX-S, vaccine
- Phase
- Phase 1
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 60 participants (actual)
- Lead sponsor
- National Institute of Allergy and Infectious Diseases (NIAID)US National Institutes of Health
- Study start
- 11 Aug 2025 (actual)
- Primary completion
- 16 Jun 2026 (actual)
- Study completion
- 16 Jun 2026 (actual)
- First posted
- 31 Jul 2025 (actual)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. The study is designed as a non-randomized, open-label, dose-escalation clinical trial evaluating three dose levels of STX-S. A sample size of 60 participants (20 participants per dose cohort) is anticipated. The primary objective is to evaluate the safety and reactogenicity of a single intramuscular injection of three different dose levels (25 ng, 50 ng, and 125 ng) of STX-S in previously vaccinated healthy adults
Detailed description
This phase 1 clinical trial will evaluate the safety, reactogenicity, and immunogenicity of STX-S in adults who have previously received a primary series and at least one booster with an authorized or licensed SARS-CoV-2 parenteral vaccine. The study is designed as a non-randomized, open-label, dose-escalation clinical trial evaluating three dose levels of STX-S. A sample size of 60 participants (20 participants per dose cohort) is anticipated. The primary objective is to evaluate the safety and reactogenicity of a single intramuscular injection of three different dose levels (25 ng, 50 ng, and 125 ng) of STX-S in previously vaccinated healthy adults. The secondary objectives are to evaluate the systemic anti-Spike humoral immune responses of a single Intramuscular (IM) injection of STX-S and to evaluate nasal mucosal Immunoglobulin A (IgA) and Immunoglobulin G (IgG) responses after study product administration.
Study design
- Primary purpose
- Prevention
- Allocation
- Non-randomised
- Intervention model
- Sequential
- Masking
- None (open label)
- Number of arms
- 3
| Arm | Type | Receives |
|---|---|---|
| Cohort 1 | Experimental | Biological: STX-SHealthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 25 ng at a volume of 0.25 mL. Three sentinel participants, aged < 50, will be enrolled over at least 2 days. The Protocol Safety Review Team (PSRT) will conduct a safety review before enrolling the remainder of the cohort. N=20 |
| Cohort 2 | Experimental | Biological: STX-SHealthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 50 ng at a volume of 0.5 mL. N=20 |
| Cohort 3 | Experimental | Biological: STX-SHealthy adult participants, 18 to 64 years of age, will be administered a single intramuscular dose of STX-S at 125 ng at a volume of 0.5 mL. N=20 |
Who may qualify
- Ages
- 18 to 64 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (15 listed)
- Provides written informed consent before initiation of any study procedures.
- Able to understand and agree to comply with planned study procedures and be available for all study visits.
- Non-pregnant adults, 18 through 64 years of age at the time of study product administration.
- Participants of childbearing potential* must agree to use or have practiced true abstinence or use at least one acceptable primary form of contraception*
- These criteria apply to females who are in a heterosexual relationship who are of childbearing potential. Not of childbearing potential include post-menopausal females (defined as having a history of amenorrhea for at least one year) or a documented status as being surgically sterile (hysterectomy, bilateral oophorectomy, or tubal ligation/salpingectomy).
Key exclusion criteria (31 listed)
- Positive SARS-CoV-2 PCR at screening.
- Abnormal vital signs (Grade 1 or higher)*:
- Grade 1 or higher is equivalent to: Systolic blood pressure (SBP) >/= 141 mmHg or </= 89 mmHg Diastolic blood pressure (DBP) >/= 91 mmHg Heart rate (HR) is >/= 101 beats per minute or </= 54 beats per minute Oral temperature >/= 38.0 degrees Celsius (100.4 degrees Fahrenheit)
- History of SARS-CoV-2 infection or receipt of any COVID-19 vaccine < 16 weeks prior to study product administration.
- Participant who is pregnant or breastfeeding.
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 |
|---|---|---|
| STX-SA proprietary vaccine developed internally by Capricor utilizing exosomes that were engineered to express spike proteins on the surface | Biological | Cohort 1, Cohort 2, Cohort 3 |
Primary outcome
Occurrence of abnormal clinical safety laboratory adverse events (AEs).
Time frame: Through Day 8
Occurrence of adverse events of special interest (AESI)
Time frame: Through 6 months post study product administration
Occurrence of medically attended adverse events (MAAEs)
Time frame: Through 6 months post study product administration
Occurrence of new onset chronic medical conditions (NOCMCs)
Time frame: Through 6 months post study product administration
Occurrence of serious adverse events (SAEs)
Time frame: Through 6 months post study product administration
Occurrence of solicited local adverse events (AEs).
Time frame: Through Day 7 post study product administration
Occurrence of solicited systemic adverse events (AEs).
Time frame: Through Day 7 post study product administration
Occurrence of unsolicited adverse events (AEs).
Time frame: Through Day 28 post study product administration
5 secondary outcomes
Nasal mucosal anti-spike binding IgA antibodies
Time frame: Day 1 through Day 91
Nasal mucosal anti-spike binding IgG antibodies
Time frame: Day 1 through Day 91
Serum Anti-spike binding Immunoglobulin A (IgA) antibody
Time frame: Day 1 through Day 181
Serum Anti-spike binding Immunoglobulin G (IgG) antibody
Time frame: Day 1 through Day 181
Serum Anti-spike neutralizing antibodies
Time frame: Day 1 through Day 181
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 26 Jun 2026.
Related trials for COVID-19
Not yet recruitingPhase 1
Phase I Open-Label Safety Trial of Pembrolizumab for Neurological Post- Acute Sequelae of SARS-CoV-2 (PD1-PASC I)
Post-Acute COVID-19 Syndrome
Active, not recruitingPhase 1
A Safety and Immunogenicity Trial of OCU500, ChAd36 Vector Encoding SARS-CoV-2 Spike Vaccine Via Intranasal and Inhalational Routes in Previously Vaccinated Adults
COVID-19
Active, not recruiting
Intervention to Address Disparate Mental Health Consequences of COVID-19 Pandemic on Latinx and African Newcomers
Mental Health Issue, Mental Health Disorder
Recruiting
Home-Based Exercise Tele-Rehabilitation After COVID-19
Post SARS-CoV2 (COVID-19)
Not yet recruitingPhase 1
A Safety, Reactogenicity and Immunogenicity Trial of RVX-sCPD9 Booster Intranasal COVID-19 Vaccine
COVID -19
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.
3 sites in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A Phase 1 study testing STX-S in people with COVID-19, run by National Institute of Allergy and Infectious Diseases (NIAID) at 3 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 15 inclusion and 31 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 Jun 2026. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 3 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 1 studies test a treatment in a small group of people for the first time or in a new way, mainly to check safety and find the right dose.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
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?
Occurrence of abnormal clinical safety laboratory adverse events (AEs). (time frame: Through Day 8). The study lists 8 primary outcomes in all. It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 Jun 2026.