SARS-CoV-2 rS/Matrix-M Adjuvant- Phase 1

Number of participants with first occurrence of positive (+) polymerase chain reaction (PCR)-confirmed SARS-CoV-2 illness with symptomatic mild, moderate, or severe COVID-19, with each symptom lasting for at least 2 consecutive days, with onset from Day 28 (7 days after second vaccination dose) through the length of the study.

Reactogenicity incidence and severity (mild, moderate or severe) recorded by all participants on their electronic patient-reported outcome diary application (eDiary) on days of vaccination and subsequent 6 days (total 7 days after each vaccine injection).

Number of participants with mild, moderate, or severe MAAEs through Day 49 i.e. 28 days after second injection of each set of vaccinations (initial and crossover).

Number of participants with mild, moderate, or severe AEs through Day 49 i.e. 28 days after second injection of each set of vaccinations (initial and crossover).

Number of participants with mild, moderate, or severe MAAEs attributed to study vaccine through specified time points approximately every 3 and 6 months.

Number of participants with mild, moderate, or severe SAEs attributed to study vaccine through specified time points approximately every 3 and 6 months.

Number of participants with mild, moderate, or severe AESIs attributed to study vaccine through specified time points approximately every 3 and 6 months.

Number of participants with mild, moderate, or severe SAEs attributed to study vaccine and AESIs through specified time points until Month 24 or the EoS.

Number of participants with mild, moderate, or severe MAAEs attributed to study vaccine and AESIs through specified time points until Month 24 or the EoS.

Number of participants with mild, moderate, or severe AESIs attributed to study vaccine and AESIs through specified time points until Month 24 or the EoS.

Number of participants with antibodies to SARS-CoV-2 NP at Day 35 to determine natural infection and to determine the incidence of asymptomatic infection acquired during study follow-up.

Number of participants who died during the study due to any cause.

Number of participants, testing serologically negative for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) at baseline, with first occurrence of positive (+) polymerase chain reaction (PCR)-confirmed SARS-CoV-2 illness with symptomatic mild, moderate, or severe COVID-19 with onset from Day 28 through the length of the study.

Reactogenicity incidence, duration, and severity (mild, moderate, severe, or potentially life-threatening) recorded by parent(s)/caregiver(s) on an electronic patient-reported outcome diary application (eDiary) on days of vaccination and subsequent 6 days (total 7 days after each vaccine injection).

Incidence and severity of MAAEs through 28 days after second injection of each set of vaccinations (initial and crossover), and after a booster dose.

Incidence and severity of unsolicited AEs through 28 days after second injection of each set of vaccinations (initial and crossover), and after a booster dose.

Incidence and severity of MAAEs attributed to study vaccine after initial vaccination at Day 0 through Month 24 or the EoS.

Incidence and severity of SAEs after initial vaccination at Day 0 through Month 24 or the EoS.

Incidence and severity of AESIs (including multisystem inflammatory syndrome in children \[MIS-C\], and myocarditis and/or pericarditis) after initial vaccination at Day 0 through Month 24 or the EoS.

Death due to any cause occurring from Day 0 to EoS.

Number of human immunodeficiency virus negative (HIV-) participants with first occurrence of positive (+) polymerase chain reaction (PCR), (+) PCR-confirmed, SARS-CoV-2 illness with symptomatic mild, moderate, or severe COVID-19 assessed from Day 28 (7 days after second vaccination dose) through the length of the study.

Number of HIV+ participants with first occurrence of (+) PCR-confirmed SARS-CoV-2 illness with symptomatic mild,moderate or severe COVID-19 assessed from Day 28 (7 days after second vaccination) through the length of the study.

Number of HIV- participants with solicited AEs, local and systemic, for 7 days following each vaccination (Days 0 and 21) by severity score, duration, and peak intensity.

Number of HIV- participants with unsolicited AEs (eg, treatment-emergent, serious, suspected unexpected serious, those of special interest, MAAEs) through Day 35 by Medical Dictionary for Regulatory Activities (MedDRA) classification, severity score, and relatedness.

Number of HIV+ participants with solicited AEs, local and systemic, for 7 days following each vaccination (Days 0 and 21) by severity score, duration, and peak intensity.

Number of HIV+ participants with unsolicited AEs (eg, treatment-emergent, serious, suspected unexpected serious, those of special interest, MAAEs) through Day 35 by MedDRA classification, severity score, and relatedness.

Serum IgG antibody levels specific for the SARS-CoV-2 rS protein antigen(s) as detected by enzyme-linked immunosorbent assay (ELISA) expressed as GMTs at Day 35.

Serum IgG antibody levels specific for the SARS-CoV-2 rS protein antigen(s) as detected by ELISA expressed as GMFRs at Day 35.

Serum IgG antibody levels specific for the SARS-CoV-2 rS protein antigen(s) as detected by ELISA expressed as SCR at Day 35. SCR is defined as the percentage of participants with a post-vaccination titer ≥ 4 fold over naïve background and ≥ 2 fold over pre existing titer.

Number of healthy adult HCW, with AESIs for 14 days post second vaccination (Day 35) by severity score, duration, and peak intensity.

Number of healthy adult HCW, with AESIs for 14 days post second vaccination (Day 70) by severity score, duration, and peak intensity.