Evaluation of Efficacy, Safety and Immunogenicity of GX-19N in Healthy Individuals Who Have Received COVID-19 Vaccines

Study Overview
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Brief Summary
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The purpose of this study is to evaluate the efficacy, safety and immunogenicity of GX-19N in healthy individuals who have received one of COVID-19 vaccine authorized for emergency use.

Official Title
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A Phase 2/3, Randomized, Double-blinded, Placebo-controlled Study to Evaluate the Efficacy, Safety, and Immunogenicity of GX-19N, A DNA Vaccine, in Healthy Individuals Who Have Received One of the COVID-19 Vaccines

Conditions
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SARS-CoV2 Infection

Intervention / Treatment
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* Biological: GX-19N
* Other: Placebo


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Adult males or females aged 18 years and above at the time of consent Healthy subjects in normal medical condition as determined by medical history, physical examination, and investigator's discretion Have previously received homologous full-dose of COVID-19 vaccine authorized for emergency use, and at least 3 months post second vaccination prior to Day 1 Negative results for SARS-COV-2 rapid antigen test at the screening period Able to comply with all study procedures and requirements Agree for blood and nasal swab samples could be collected throughout the study period, including surveillance visit Exclusion Criteria: Unable to follow clinical and follow-up procedures Acute fever with temperature above 38℃, coughing, breathing difficulty, chills, muscle ache, headache, sore throat, loss of smell, or loss of taste within 72 hours prior to the vaccination History of SARS-CoV-2 infection or have experienced prior administration of an investigational coronavirus (SARS-CoV, MERS-CoV) vaccine History of a malignant disease within the past 5 years Immune dysfunction, including immunodeficiency disorder, or family history of such conditions (Except stable/well-controlled HIV-positive participants) Have received immunoglobulin or blood-derived products within 3 months prior to the vaccination or are scheduled to receive them during the study period Have been dependent on antipsychotic drugs and narcotic analgesics within 6 months prior to the vaccination History or are suspected of alcohol or drug dependency History of hypersensitivity or allergic reactions including anaphylaxis A current or history of clinically significant chronic cardiovascular, endocrine, gastrointestinal, hepatic (including hepatitis B and C), renal, neurological, respiratory, psychiatric or other medical disorders not excluded by other exclusion criteria, that are assessed by the investigator Hemophiliacs or people using anticoagulants who are at a risk of serious bleeding from IM injection Have received or plans to receive other vaccination(s) within 28 days prior to or during study duration (except for influenza vaccine which is not allowed within 14 days before, or 4 weeks after final dose of IP) Have taken an immunosuppressant or immune-modifying drug within 3 months prior to the vaccination; chronic administration (defined as more than 14 continuous days) of immunosuppressant medication within the past 3 months, except topical steroids or short-term oral steroids (course lasting ≤ 14 days) Female who are pregnant or breastfeeding; however, participation is possible if breastfeeding is discontinued prior to participation in the study Have received or have plans to receive other investigational drug(s) while participating in another clinical study or bioequivalence study within 28 days prior to vaccination Not consent to the use of effective contraception at least 90 days after the last vaccination Lack of acceptable sites available for IM injection and EP Deemed ineligible by the investigator based on other clinically significant medical or psychiatric findings

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Prevention
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Triple


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: GX-19N<br>GX-19N will be intramusculary administered via EP on day 1 and day 29. | Biological: GX-19N<br>* DNA vaccine expressing SARS-CoV-2 S-protein antigen including the Nucleocapsid protein (NP) antigen<br>|
| Placebo Comparator: Placebo<br>Placebo will be intramusculary administered via EP on day 1 and day 29 | Other: Placebo<br>* GX-19N formulation buffer<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| First occurrence of COVID-19 at least 14 days after the second vaccination | Symptomatic, virologically confirmed COVID-19 as described in the study | Up to 1 year after first vaccination | 
| Incidence of severe solicited adverse events (AEs) | Percentage of subjects reporting grade 3 or higher AEs after each vaccination | Up to 7 days after each vaccination | 
| Incidence of AEs and Serious AEs (SAEs) after each vaccination | Percentage of subjects reporting AEs and SAEs after each vaccination | Up to 1 month after each vaccination | 
| Incidence of SAE, and Adverse events of special interest (AESIs), which relevant to COVID-19 including possible vaccine-enhanced disease | SAE and AESIs reported in all subjects at any time after the first vaccination | Up to 1 year after first vaccination | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| First occurrence of severe COVID-19 at least 14 days after the second vaccination | Symptomatic, virologically confirmed severe COVID-19 as described in the study | Up to 1 year after first vaccination | 
| Cell-mediated immune responses after vaccination | Antigen-specific T cell response in a subset of Phase 2/3 | Up to 1 year after first vaccination | 
| Antibody responses after vaccination | Analysis of binding antibodies and neutralizing antibodies in a subset of Phase 2/3 | Up to 1 year after first vaccination |