This is a Phase 1/2, randomized, observer-blind study in healthy adults. The study will evaluate the safety, reactogenicity, and immunogenicity of 3 SARS-CoV-2 self-amplifying RNA vaccine candidates against COVID-19 in adults previously vaccinated and not previously vaccinated against SARS-CoV-2.
The study will initially enroll approximately 72 adult participants into 2 cohorts (A and B). Cohort A is further sub-divided into two sub-cohorts which include 12 participants who are seronegative, not previously vaccinated at screening (Sub-cohort A1) and 24 participants who are seropositive, not previously vaccinated at screening (Sub-cohort A2). Within the first cohort (Cohort A), Sub-cohort A1 will include a total of 12 adult participants ≥21 to ≤65 years of age who have not been previously vaccinated with a SARS-CoV-2 vaccine. Sub-cohort A2 will include a total of 24 adult participants ≥21 to ≤65 years of age who have not been previously vaccinated with a SARS-CoV-2 vaccine. Study vaccines will be given as 2 doses separated by 28 days. The second cohort (Cohort B) will include a total of 36 adult participants ≥21 to ≤65 years of age who have been previously vaccinated (5 months or longer prior to study enrollment) with SARS-CoV-2 vaccine. Study vaccines will be given as single doses. Additional cohorts may increase the age range of participants up to 80 years of age.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
QUADRUPLE
Enrollment
72
Arcturus Investigational Site 202
Wichita, Kansas, United States
Arcturus Investigational Site 201
Kansas City, Missouri, United States
Arcturus Investigational Site 101
Singapore, Singapore
Arcturus Investigational Site 301
Diepkloof, Soweto, South Africa
Number of Participants Reporting Solicited Local or Systemic Adverse Events (AEs)
Solicited local AEs were defined as injection site erythema, injection site pain, injection site induration, and injection site tenderness. Solicited systemic AEs were defined as arthralgia, chills, diarrhea, dizziness, fatigue, fever (categorized by measured body temperature), headache, myalgia, nausea and vomiting. Data are reported for the number of participants with solicited local and solicited systemic AEs. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to Day 8 (7 days after first vaccine administration for Cohorts A1, A2 and B), and up to Day 36 (7 days after second vaccine administration for Cohorts A1 and A2)
Number of Participants Reporting Unsolicited AEs
Unsolicited AEs were defined as any spontaneously reported or discovered AE. Data are reported for the number of participants with unsolicited AEs. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
Time frame: Up to Day 29 (28 days after vaccine administration for Cohort B), and up to Day 57 (up to 28 days after each vaccine administration for Cohorts A1 and A2)
Number of Participants Reporting Medically Attended Adverse Events (MAAEs), AEs Leading to Discontinuation From Study Vaccine/Study Withdrawal, or Serious Adverse Events (SAEs)
An MAAE was an AE that led to an unscheduled visit (including a telemedicine visit) with a health care provider (HCP) (e.g., nurse, nurse practitioner, physician's assistant, physician), including visits to a study site for unscheduled assessments (e.g., rash assessment, abnormal laboratory follow up, coronavirus disease 2019 \[COVID-19\]) and visits to HCPs external to the study site (e.g., urgent care, primary care physician). An SAE was defined as any event that resulted in death, was immediately life-threatening, required inpatient hospitalization or prolongation of existing hospitalization, resulted in persistent or significant disability/incapacity, or was a congenital anomaly/birth defect. A summary of all Serious Adverse Events and Other Adverse Events (nonserious) regardless of causality is located in the 'Reported Adverse Events' Section.
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Time frame: Through Final Visit (365 days after last study vaccine dose); up to a maximum of approximately 394 days
Severe Acute Respiratory Syndrome-Coronavirus-2 (SARS-CoV-2) Serum Neutralizing Antibody Levels, Expressed as Geometric Mean Concentration (GMC)
Blood samples were collected to assess participants' immune response. GMC data are reported for the pseudoviral D614G variant. Data are reported in international units per milliliter (IU/mL).
Time frame: Baseline, Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2; Baseline, Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as GMC
Blood samples were collected to assess participants' immune response. GMC data are reported for the pseudoviral B.1.351 (beta) variant. Data are reported in arbitrary units per milliliter (AU/mL).
Time frame: Baseline, Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2; Baseline, Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as Geometric Mean Fold Rise (GMFR)
Blood samples were collected to assess participants' immune response. GMFR data are reported for the pseudoviral D614G variant.
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
SARS-CoV-2 Serum Neutralizing Antibody Levels, Expressed as GMFR
Blood samples were collected to assess participants' immune response. GMFR data are reported for the pseudoviral B.1.351 (beta) variant.
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Serum Neutralizing Antibody Levels (Pseudoviral D614G Variant)
Blood samples were collected to assess participants' immune response. Data are reported for the pseudoviral D614G variant.
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Serum Neutralizing Antibody Levels (Pseudoviral B.1.351 [Beta] Variant)
Blood samples were collected to assess participants' immune response. Data are reported for the pseudoviral B.1.351 (beta) variant.
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
GMC Ratio (ARCT-165 vs ARCT-154 and ARCT-021 vs ARCT-154)
Blood samples were collected to assess participants' immune response. Data are reported for the pseudoviral D614G Variant, B.1.351 Variant, B.1.617.2 Variant, BA.1 Variant for the GMC ratio of ARCT-165 vs ARCT-154 and ARCT-021 vs ARCT-154. Data are reported for the ARCT-165 and ARCT-021 arms (vs ARCT-154 values).
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohorts A1 and A2, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
GMC Ratio (ARCT-021 vs ARCT-165 Cohorts A1 and B)
Blood samples were collected to assess participants' immune response. Data are reported for the pseudoviral D614G Variant, B.1.351 Variant, B.1.617.2 Variant, BA.1 Variant for the GMC ratio of ARCT-021 vs ARCT-165. Data are reported for the ARCT-021 arm (vs ARCT-165 values).
Time frame: Days 29, 57, 209, Final Visit (approx. Day 394) for Cohort A1, and Days 15, 29, 91, 181, 271 and Final Visit (approx. Day 366) for Cohort B
SARS-CoV-2 Full-length Spike and Receptor-binding Domain (RBD) Binding Antibody Levels, Expressed as GMCs
Spike binding antibody levels expressed as GMCs are reported for ancestral, D614G, and B.1.351 variants and RBD binding antibodies for ancestral strain.
Time frame: Baseline and Day 57 for Cohorts A1 and A2, Baseline and Day 15 for Cohort B
Changes in SARS-CoV-2 Full-length Spike and RBD Binding Antibody Levels, Expressed as GMFRs
Spike binding antibody levels expressed as GMFRs are reported for ancestral, D614G, and B.1.351 variants and RBD binding antibody levels expressed as GMFR for ancestral strain.
Time frame: Day 57 for Cohorts A1 and A2, Day 15 for Cohort B
Number of Participants Achieving Greater Than or Equal to 4-fold Rise From Before Vaccination in SARS-CoV-2 Full-length Spike and RBD Binding Antibody Levels
Data are reported for ancestral, D614G, and B.1.351 variants for Spike binding antibodies and ancestral for RBD binding antibodies.
Time frame: Day 57 for Cohorts A1 and A2, Day 15 for Cohort B