NCT06799013 · HDT Bio
Safety and Immunogenicity of a Self-Amplifying RNA Vaccine Against Crimean-Congo Hemorrhagic Fever
What this study is about
The goal of this clinical trial is to assess the safety, tolerability and immunogenicity of three dosage levels, and a single or two-dose administration regimen, of the experimental HDT-321 product administered intra-muscularly.
View original scientific description
The goal of this clinical trial is to assess the safety, tolerability and immunogenicity of three dosage levels, and a single or two-dose administration regimen, of the investigational HDT-321 product administered intra-muscularly.
Interventions
BIOLOGICAL
10 ug HDT 321
HDT-321 Investigational Vaccine (a Nanoparticle Carrier-Formulated self-amplifying RNA encoding the NP of CCHFV)
BIOLOGICAL
25ug HDT-321
HDT-321 Investigational Vaccine (a Nanoparticle Carrier-Formulated self-amplifying RNA encoding the NP of CCHFV)
BIOLOGICAL
50ug HDT-321
HDT-321 Investigational Vaccine (a Nanoparticle Carrier-Formulated self-amplifying RNA encoding the NP of CCHFV)
Primary outcome measures
Solicited local and systemic adverse events (AEs)
Time frame: Day 1-7 post administration
Frequency and grade of solicited local and systemic AEs during the 7-day follow-up period after each study injection (i.e. the day of administration and 6 subsequent days).
Unsolicited study product related adverse events
Time frame: Day 1-28 post administration
Frequency and grade of unsolicited study product related AEs reported during the 28-day follow-up period after each study injection.
Laboratory abnormalities
Time frame: Day 1-7 post administration
Occurrence of laboratory abnormalities at 7 days post injection visit (increased or decreased outside normal ranges, as determined by the FDA Guidance for Industry Toxicity Grading Scale for Healthy Adults Enrolled in Preventive Vaccine Clinical Trials, 2007)
Serious AEs, AEs of Special Interest, Medically Attended AEs, and New-Onset of Chronic Diseases
Time frame: Day 1 to end of study participation (Day 394)
Frequency and grade of Serious AEs (SAEs), AEs of Special Interest (AESIs), Medically-Attended AEs (MAAEs), and New-Onset of Chronic Diseases (NOCDs) during the duration of participation in the study.
Who can participate
This study lists these criteria on ClinicalTrials.gov. A study coordinator reviews eligibility during screening — this page does not determine whether you qualify.
Inclusion criteria
- Males and non-pregnant females 18 to 64 years of age at the time of signing the ICF.
- Body mass index (BMI) 17 to 35 inclusive at screening.
- Considered by the PI or designee to be in good general health as determined by medical history, physical examination, vital sign measurements\*, and clinical laboratory assessments conducted no more than 30 days prior to the first study injection administration.
- Screening laboratory values within the laboratory reference ranges or considered non-clinically significant (NCS) if within Grade 1 severity on the toxicity grading scale.
- Negative human immunodeficiency virus (HIV) 1/2 antibody, hepatitis B surface antigen (HBsAg), and hepatitis C virus (HCV) antibody.
- Women of childbearing potential must agree to use or have practiced true abstinence or use at least one acceptable primary form of contraception3 for at least 30 days prior to the first injection and for 60 days after the last injection. Female participants of childbearing potential must have a negative serum pregnancy test at screening and a negative urine pregnancy test on the day of and prior to each study injection.
- Able to understand and comply with planned study procedures and willing to be available for all study required procedures, visits, and telephone calls for the duration of the study.
- Provide written informed consent before initiation of any study procedures.
- Willing to abstain from donating whole blood or blood derivatives 30 days prior to screening and for the duration of the study.
- Willing to refrain from receiving any licensed vaccine within 28 days prior to and after scheduled study injections.
Exclusion criteria
- Any medical disease or condition that, in the opinion of the participating site PI or appropriate sub-investigator, precludes study participation. Including Acute, subacute, intermittent, or chronic medical diseases or conditions that would place the subject at an unacceptable risk of injury, render the subject unable to meet the requirements of the protocol, or may interfere with the evaluation of responses or the subject's successful completion of the trial. Significant respiratory disease (COPD) requiring daily medications, asthma that is not well controlled, significant cardiovascular disease, history of myocarditis or pericarditis, myocardial infarction, coronary artery bypass surgery or stent placement, or uncontrolled cardiac arrhythmia, Neurological or neurodevelopmental conditions, ongoing malignancy or recent diagnosis of malignancy in the last five years excluding basal cell and squamous cell carcinoma of the skin, blood dyscrasias or significant disorder of coagulation, chronic liver disease, including fatty liver, autoimmune disease, including localized or history of psoriasis or hypothyroidism without a defined non-autoimmune cause and Immunodeficiency of any cause.
- Abnormal screening electrocardiogram (ECG)
- History of hypersensitivity or severe reactions to previous vaccinations
- History of hypersensitivity or severe reactions to products known to contain polyethylene glycol (PEG).
- Allergy to antibiotics structurally similar to kanamycin (including but not limited to neomycin, streptomycin, tobramycin, and gentamycin).
- Chronic administration (defined as more than 14 days in total) of immunosuppressants or other immunemodifying drugs within 6 months prior to the first study injection (for corticosteroids: prednisone ≥20 mg/day or equivalent). Intra-articular, inhaled, nasal, and topical steroids are allowed.
- Received immunoglobulins or any blood products within 60 days prior to enrollment/Day 1.
- Donated blood products within 30 days prior to enrollment/Day 1.
- Received an investigational or non-registered medicinal product within 30 days prior to screening.
- Currently enrolled, or plan to participate, in another clinical trial with an investigational agent to be received during the study period.
- Received or plans to receive any non-study vaccine within 28 days before and after each study injection.
- Febrile illness\*, as determined by the participating site PI or appropriate sub-investigator, with or without fever (oral temperature ≥38.0°C/100.4°F), within 24 hours prior to each study injection.
- Current heavy smoking/vaping (defined as 1 pack or more of cigarettes a day or vaping equivalent\*). \*1-2 mL of 20 mg/mL of nicotine salt
- Known or suspected alcohol or illicit drug abuse within the past 12 months prior to Study Day 1.
- Breastfeeding or plans to breastfeed from the time of the first vaccination through 60 days after the last study injection.
- Participants unlikely to cooperate with the requirements of the study protocol.
Where
- San Antonio, Texas
Collaborators
DFNet Research Inc., Technical Resources International, Inc., BioAgilytix Labs, LLC, The University of Texas Medical Branch, Galveston, Clinical Trials of Texas, Inc., Quest Laboratories
Related conditions & keywords
Frequently asked questions
What is a clinical trial?
A clinical trial is a research study that tests new medical treatments, drugs, devices, or procedures to determine their safety and effectiveness. Trials are carefully designed and monitored to protect participants while advancing medical knowledge.
Is it safe to participate?
Clinical trials follow strict safety guidelines and ethical standards. Trials must be reviewed and approved, and participants are closely monitored by medical professionals throughout the study. You can withdraw at any time if you choose.
Will I be compensated?
Many clinical trials offer compensation for your time, travel expenses, and inconvenience. The specific compensation varies by study and will be discussed during the screening process. All study-related medical care is typically provided at no cost to participants.
Will I receive a placebo instead of treatment?
When effective treatment exists, participants typically receive either the standard treatment plus the study intervention, or the standard treatment plus placebo. You would not be denied effective care. Placebos are primarily used when no proven treatment is available, or in addition to standard care. Your trial consent form will clearly explain what treatments you may receive.
Can I leave a trial if I change my mind?
Absolutely. Participation in clinical trials is completely voluntary. You have the right to withdraw from the study at any time, for any reason, without penalty or loss of benefits to which you are otherwise entitled.
How long does a clinical trial last?
Trial duration varies widely depending on the study design and purpose. Some trials last just a few weeks, while others may continue for months or years. The study coordinator will provide specific timeline information during your screening call.
Data: ClinicalTrials.gov · synced Jul 28, 2025 · Source of record for eligibility and locations