Trial Outcomes & Findings for Chimpanzee Adenovirus and Self-Amplifying mRNA Prime-Boost Prophylactic Vaccines Against SARS-CoV-2 in Healthy Adults (NCT NCT04776317)

Results Overview

Number of participants that experienced any NOCMCs during the course of the study

Recruitment status

COMPLETED

Study phase

PHASE1

Target enrollment

81 participants

Primary outcome timeframe

Day 1 to study completion through up to 1 year post last dose

Results posted on

2025-05-16

Participant Flow

Participants were recruited from 4 distinct US-based Infectious Diseases Clinical Research Consortium (IDCRC) sites. The first participant was enrolled on March 25, 2021, and the last participant was enrolled on September 29, 2022.

Stage 1 studied dose escalation of homologous and heterologous prime-boost vaccination schedules in healthy naïve adult participants. Stage 2 studied booster vaccination(s) in adult participant who previously received Coronavirus Disease 2019 (COVID-19) Emergency Use Authorization (EUA)/licensed vaccines.

Participant milestones

Participant milestones
Measure	Stage 1 (Naïve) Group 1 5 x 10\^10 viral particles of ChAdV68-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 30 mcg of SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 29 in participants from 18 to 60 years of age. N=4 ChAdV68-S: Chimpanzee Adenovirus serotype 68 - Spike (ChAdV68-S) is a replication-defective, E1, E3 E4Orf2-4 deleted adenoviral vector based on chimpanzee adenovirus 68 (C68, 68/SAdV-25, originally designated as Pan 9), which belongs to the sub-group E adenovirus family. A single 0.5 mL intramuscular injection will be administered in the deltoid muscle. SAM-LNP-S: Self-Amplifying mRNA - Lipid Nanoparticles - Spike (SAM-LNP-S) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 mL or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 1 (Naïve) Group 3A 30 mcg of SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 30 mcg of SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 29 in participants from 18 to 60 years of age. N=3 SAM-LNP-S: Self-Amplifying mRNA - Lipid Nanoparticles - Spike (SAM-LNP-S) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 mL or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 1 (Naïve) Group 3B 30 mcg SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 3 mcg of SAM-LNP-S administered through 0.25 mL intramuscular injection in the deltoid muscle on or after Day 85 and no later than Day 130 in participants from 18 to 60 years of age. N=7 SAM-LNP-S: Self-Amplifying mRNA - Lipid Nanoparticles - Spike (SAM-LNP-S) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 mL or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 1 (Naïve) Group 4 10 mcg of SAM-S-TCE administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 3 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on or after Day 85 and no later than Day 130 in participants from 18 to 60 years of age. N=3 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (SAM-S-TCE Boosts After EUA/Licensed mRNA COVID-19 Vaccines) Group 5 3 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on Day 1 in participants from 18 to 60 years of age. N=10 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (SAM-S-TCE Boosts After EUA/Licensed mRNA COVID-19 Vaccines) Group 6 6 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on Day 1 in participants from 18 to 60 years of age. N=10 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 3 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=8 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B 6 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=8-12 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B 10 mcg of SAM-S-TCE administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=8-12 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 5 x 10\^10 viral particles of ChAdV68-S-TCE administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=7-10 ChAdV68-S-TCE: Chimpanzee Adenovirus 68 - Spike plus additional SARS-CoV-2 T cell epitopes (ChAdV68-S-TCE) is a replication-defective, E1, E3 E4Orf2-4 deleted adenoviral vector based on chimpanzee adenovirus 68 (C68, 68/SAdV-25, originally designated as Pan 9), which belongs to the sub-group E adenovirus family. A single 0.5- or 1.0-mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 1 x 10\^11 viral particles of ChAdV68-S-TCE administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=7-10 ChAdV68-S-TCE: Chimpanzee Adenovirus 68 - Spike plus additional SARS-CoV-2 T cell epitopes (ChAdV68-S-TCE) is a replication-defective, E1, E3 E4Orf2-4 deleted adenoviral vector based on chimpanzee adenovirus 68 (C68, 68/SAdV-25, originally designated as Pan 9), which belongs to the sub-group E adenovirus family. A single 0.5- or 1.0-mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 5 x 10\^11 viral particles of ChAdV68-S-TCE administered through 1.0 mL intramuscular injection in the deltoid muscle on Day 1 in participants older than 60 years of age. N=7-10 ChAdV68-S-TCE: Chimpanzee Adenovirus 68 - Spike plus additional SARS-CoV-2 T cell epitopes (ChAdV68-S-TCE) is a replication-defective, E1, E3 E4Orf2-4 deleted adenoviral vector based on chimpanzee adenovirus 68 (C68, 68/SAdV-25, originally designated as Pan 9), which belongs to the sub-group E adenovirus family. A single 0.5- or 1.0-mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.
Overall Study STARTED	4	3	7	3	10	10	8	10	10	7	7	2
Overall Study COMPLETED	4	2	6	3	9	10	8	10	10	7	7	2
Overall Study NOT COMPLETED	0	1	1	0	1	0	0	0	0	0	0	0

Reasons for withdrawal

Reasons for withdrawal
Measure	Stage 1 (Naïve) Group 3A 30 mcg of SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 30 mcg of SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 29 in participants from 18 to 60 years of age. N=3 SAM-LNP-S: Self-Amplifying mRNA - Lipid Nanoparticles - Spike (SAM-LNP-S) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 mL or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 1 (Naïve) Group 3B 30 mcg SAM-LNP-S administered through 0.5 mL intramuscular injection in the deltoid muscle on Day 1 and 3 mcg of SAM-LNP-S administered through 0.25 mL intramuscular injection in the deltoid muscle on or after Day 85 and no later than Day 130 in participants from 18 to 60 years of age. N=7 SAM-LNP-S: Self-Amplifying mRNA - Lipid Nanoparticles - Spike (SAM-LNP-S) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 mL or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.	Stage 2 (SAM-S-TCE Boosts After EUA/Licensed mRNA COVID-19 Vaccines) Group 5 3 mcg of SAM-S-TCE administered through 0.25 mL intramuscular injection in the deltoid muscle on Day 1 in participants from 18 to 60 years of age. N=10 SAM-LNP-S-TCE: Self-Amplifying mRNA - Lipid Nanoparticles -Spike plus additional SARS-CoV-2 T cell epitopes (SAM-S-TCE) is a SAM vector based on Venezuelan Equine Encephalitis Virus (VEEV). A single 0.25 or 0.5 mL (depending on dose level) intramuscular injection will be administered in the deltoid muscle. When possible, the prime vaccine and boost vaccine should be administered in different arms. Sodium Chloride, 0.9%: The diluent used for this study will be 0.9% Sodium Chloride Injection, USP, and is a sterile, nonpyrogenic, isotonic solution of sodium chloride and water for injection. Each milliliter (mL) contains sodium chloride 9 mg. It contains no bacteriostat, antimicrobial agent or added buffer and is supplied only in single-dose containers to dilute or dissolve drugs for injection. 0.308 mOsmol/mL (calc.). 0.9% Sodium Chloride Injection, USP contains no preservatives.
Overall Study Physician Decision	1	0	0
Overall Study Protocol Violation	0	1	0
Overall Study Withdrawal by Subject	0	0	1

Baseline Characteristics

Chimpanzee Adenovirus and Self-Amplifying mRNA Prime-Boost Prophylactic Vaccines Against SARS-CoV-2 in Healthy Adults

Baseline characteristics by cohort

Baseline characteristics by cohort
Measure	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3B n=7 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 3 µg SAM-S.	Stage 1 (Naïve) Group 4 n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 10 µg SAM-S-TCE followed by 3 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After EUA/Licensed mRNA COVID-19 Vaccines) Group 5 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, 18-60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After EUA/Licensed mRNA COVID-19 Vaccines) Group 6 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, 18-60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Total n=81 Participants Total of all reporting groups
Age, Continuous	32.5 years STANDARD_DEVIATION 8.9 • n=5 Participants	23.3 years STANDARD_DEVIATION 8.4 • n=7 Participants	45.4 years STANDARD_DEVIATION 11.7 • n=5 Participants	29.3 years STANDARD_DEVIATION 13.6 • n=4 Participants	32.9 years STANDARD_DEVIATION 12.6 • n=21 Participants	34.0 years STANDARD_DEVIATION 8.7 • n=8 Participants	63.4 years STANDARD_DEVIATION 2.8 • n=8 Participants	67.8 years STANDARD_DEVIATION 4.7 • n=24 Participants	66.0 years STANDARD_DEVIATION 4.5 • n=42 Participants	69.1 years STANDARD_DEVIATION 7.1 • n=42 Participants	64.7 years STANDARD_DEVIATION 5.3 • n=42 Participants	67.5 years STANDARD_DEVIATION 3.5 • n=42 Participants	51.0 years STANDARD_DEVIATION 18.2 • n=36 Participants
Sex: Female, Male Female	0 Participants n=5 Participants	0 Participants n=7 Participants	4 Participants n=5 Participants	0 Participants n=4 Participants	6 Participants n=21 Participants	7 Participants n=8 Participants	5 Participants n=8 Participants	6 Participants n=24 Participants	7 Participants n=42 Participants	5 Participants n=42 Participants	2 Participants n=42 Participants	0 Participants n=42 Participants	42 Participants n=36 Participants
Sex: Female, Male Male	4 Participants n=5 Participants	3 Participants n=7 Participants	3 Participants n=5 Participants	3 Participants n=4 Participants	4 Participants n=21 Participants	3 Participants n=8 Participants	3 Participants n=8 Participants	4 Participants n=24 Participants	3 Participants n=42 Participants	2 Participants n=42 Participants	5 Participants n=42 Participants	2 Participants n=42 Participants	39 Participants n=36 Participants
Ethnicity (NIH/OMB) Hispanic or Latino	0 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	1 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	2 Participants n=36 Participants
Ethnicity (NIH/OMB) Not Hispanic or Latino	4 Participants n=5 Participants	2 Participants n=7 Participants	7 Participants n=5 Participants	3 Participants n=4 Participants	10 Participants n=21 Participants	9 Participants n=8 Participants	8 Participants n=8 Participants	10 Participants n=24 Participants	10 Participants n=42 Participants	7 Participants n=42 Participants	7 Participants n=42 Participants	2 Participants n=42 Participants	79 Participants n=36 Participants
Ethnicity (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants
Race (NIH/OMB) American Indian or Alaska Native	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	1 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=36 Participants
Race (NIH/OMB) Asian	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	1 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=36 Participants
Race (NIH/OMB) Native Hawaiian or Other Pacific Islander	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants
Race (NIH/OMB) Black or African American	0 Participants n=5 Participants	1 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=36 Participants
Race (NIH/OMB) White	4 Participants n=5 Participants	2 Participants n=7 Participants	7 Participants n=5 Participants	3 Participants n=4 Participants	9 Participants n=21 Participants	9 Participants n=8 Participants	8 Participants n=8 Participants	10 Participants n=24 Participants	10 Participants n=42 Participants	6 Participants n=42 Participants	7 Participants n=42 Participants	2 Participants n=42 Participants	77 Participants n=36 Participants
Race (NIH/OMB) More than one race	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=36 Participants
Race (NIH/OMB) Unknown or Not Reported	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	0 Participants n=24 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=42 Participants	0 Participants n=36 Participants
Previous COVID-19 Infection Previous infection	0 Participants n=5 Participants	0 Participants n=7 Participants	0 Participants n=5 Participants	0 Participants n=4 Participants	0 Participants n=21 Participants	0 Participants n=8 Participants	0 Participants n=8 Participants	2 Participants n=24 Participants	2 Participants n=42 Participants	0 Participants n=42 Participants	1 Participants n=42 Participants	0 Participants n=42 Participants	5 Participants n=36 Participants
Previous COVID-19 Infection No previous infection	4 Participants n=5 Participants	3 Participants n=7 Participants	7 Participants n=5 Participants	3 Participants n=4 Participants	10 Participants n=21 Participants	10 Participants n=8 Participants	8 Participants n=8 Participants	8 Participants n=24 Participants	8 Participants n=42 Participants	7 Participants n=42 Participants	6 Participants n=42 Participants	2 Participants n=42 Participants	76 Participants n=36 Participants
BMI	25.23 kg/m^2 STANDARD_DEVIATION 3.48 • n=5 Participants	21.03 kg/m^2 STANDARD_DEVIATION 3.18 • n=7 Participants	24.51 kg/m^2 STANDARD_DEVIATION 2.11 • n=5 Participants	25.57 kg/m^2 STANDARD_DEVIATION 3.44 • n=4 Participants	23.46 kg/m^2 STANDARD_DEVIATION 2.94 • n=21 Participants	24.79 kg/m^2 STANDARD_DEVIATION 3.05 • n=8 Participants	26.03 kg/m^2 STANDARD_DEVIATION 4.46 • n=8 Participants	24.77 kg/m^2 STANDARD_DEVIATION 4.31 • n=24 Participants	29.26 kg/m^2 STANDARD_DEVIATION 2.69 • n=42 Participants	23.33 kg/m^2 STANDARD_DEVIATION 4.35 • n=42 Participants	26.61 kg/m^2 STANDARD_DEVIATION 4.74 • n=42 Participants	26.55 kg/m^2 STANDARD_DEVIATION 2.47 • n=42 Participants	25.00 kg/m^2 STANDARD_DEVIATION 3.80 • n=36 Participants

PRIMARY outcome

Timeframe: Day 1 to study completion through up to 1 year post last dose

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants that experienced any NOCMCs during the course of the study

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any New-onset Chronic Medical Conditions (NOCMCs)	0 Participants	1 Participants	2 Participants	0 Participants	0 Participants	2 Participants	1 Participants	1 Participants	1 Participants	0 Participants	1 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 to study completion through up to 1 year post last dose

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants that experienced any PIMMCs during the course of the study

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any Potentially Immune-mediated Medical Conditions (PIMMCs)	0 Participants	0 Participants	2 Participants	0 Participants	0 Participants	1 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 to study completion through up to 1 year post last dose

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants that experienced any MAAEs during the course of the study

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any Medically Attended Adverse Events (MAAEs)	1 Participants	4 Participants	4 Participants	0 Participants	1 Participants	4 Participants	3 Participants	3 Participants	5 Participants	3 Participants	1 Participants	0 Participants

PRIMARY outcome

Timeframe: Through 7 days post each study vaccination

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants that experienced any laboratory AE

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any Laboratory AE	3 Participants	8 Participants	8 Participants	4 Participants	3 Participants	7 Participants	7 Participants	8 Participants	10 Participants	6 Participants	5 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 to study completion through up to 1 year post last dose

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

The number of participants that experience any SAEs from Day 1 to study completion. An AE or suspected adverse reaction is considered serious if, in the view of either the participating site PI or appropriate sub-investigator or the sponsor, it results in: death, a life-threatening AE, inpatient hospitalization or prolongation of existing hospitalization, a persistent or significant incapacity or substantial disruption of the ability to conduct normal life functions, or a congenital anomaly/birth defect.

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any Serious Adverse Events (SAEs)	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants	0 Participants

PRIMARY outcome

Timeframe: Day 1 through Day 8 for Groups 5, 6, 9, 10, 11, 13, 14 and 15 and through 7 days post any vaccination for Groups 1, 3A, 3b and 4.

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants who experienced any systemic solicited AEs through 7 days post any vaccination. Systemic events include: fatigue, headache, myalgia, arthralgia, nausea, chills and fever.

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Systemic Solicited Reactogenicity Adverse Events (AEs)	3 Participants	10 Participants	10 Participants	4 Participants	3 Participants	7 Participants	8 Participants	10 Participants	10 Participants	3 Participants	5 Participants	2 Participants

PRIMARY outcome

Timeframe: Day 1 through Day 8 for Groups 5, 6, 9, 10, 11, 13, 14 and 15 and through 7 days post any vaccination for Groups 1, 3A, 3b and 4.

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants who experienced any local solicited AEs through 7 days post any vaccination. Local events include: pain at injection site, erythema, and induration.

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Local Solicited Reactogenicity Adverse Events (AEs)	3 Participants	10 Participants	8 Participants	4 Participants	3 Participants	7 Participants	5 Participants	8 Participants	9 Participants	1 Participants	2 Participants	1 Participants

PRIMARY outcome

Timeframe: Day 1 through Day 29 for Groups 5, 6, 9, 10, 11, 13, 14 and 15 and 28 days post any vaccination for Groups 1, 3A, 3b and 4.

Population: The Safety Analysis population for the study includes all participants who received one dose of vaccine.

Number of participants who experienced any unsolicited AEs through 28 days post vaccination

Outcome measures

Outcome measures
Measure	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 10A,B n=3 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 6 µg SAM-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 1 (Naïve) Group 1 n=4 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 5 x 10\^10 vp ChAd-S followed by 30 µg SAM-S.	Stage 1 (Naïve) Group 3A n=3 Participants Covid-19 Vaccine and infection Naïve, 18-60years old; received intramuscular (IM) injection of 30 µg SAM-S followed by 30 µg SAM-S.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 9 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 3 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=8 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.	Stage 2 (SAM-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 11A,B n=10 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 10 µg SAM-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 13 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^10 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 14 n=7 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 1x10\^11 vp ChAd-S-TCE.	Stage 2 (ChAd-S-TCE Boosts After Approved/Licensed mRNA COVID-19 Vaccines) Group 15 n=2 Participants Previously (\>/=112 days) dosed with Emergency Use Authorization (EUA)/licensed mRNA vaccine, greater than 60 years old, received a single intramuscular (IM) injection of 5x10\^11 vp ChAd-S-TCE.
Frequency of Any Unsolicited Adverse Events (AEs)	3 Participants	10 Participants	8 Participants	1 Participants	2 Participants	6 Participants	7 Participants	7 Participants	8 Participants	6 Participants	5 Participants	2 Participants

SECONDARY outcome

Timeframe: Day 29 Post Vaccination 1, Day 57 Post Vaccination 1 (29 Days Post Vaccination 2), Day 209 Post Vaccination 1 (181 Days Post Vaccination 2), Day 394 Post Vaccination 1 (366 Days Post Vaccination 2)