COVID-19 Study Assessing the Efficacy and Safety of Anti-Spike SARS CoV-2 Monoclonal Antibodies for Prevention of SARS CoV-2 Infection Asymptomatic in Healthy Adults and Adolescents Who Are Household Contacts to an Individual With a Positive SARS-CoV-2 RT-PCR Assay

Primary Objectives:

Cohort A:

• To evaluate the efficacy of REGN10933+REGN10987 compared to placebo in preventing symptomatic SARS-CoV-2 infection (broad-term) confirmed by RT-qPCR

Cohort A and Cohort A1:

• To evaluate the safety and tolerability of REGN10933+REGN10987 following subcutaneous (SC) administration compared to placebo

Cohort B • To evaluate the efficacy of REGN10933+REGN10987 compared to placebo in preventing COVID-19 symptoms (broad-term)

Cohort B and Cohort B1

• To evaluate the safety and tolerability of REGN10933+REGN10987 following SC administration compared to placebo

Cohort A: adult and adolescent subjects (≥12 years) who are SARS -CoV-2 RT-qPCR negative at baseline

Cohort A1: pediatric subjects (\<12 years) who are SARS-CoV-2 RT--qPCR negative at baseline

Cohort B: adult and adolescent subjects (≥12 years) who are SARS -CoV-2 RT-qPCR positive at baseline

Cohort B1: pediatric subjects (\<12 years) who are SARS-CoV-2 RT--qPCR positive at baseline

Eligibility Criteria:
Key Inclusion Criteria:

1. Adult subjects 18 years of age (irrespective of weight) and above at the signing of informed consent or adolescent participants ≥12 to \<18 years of age, or pediatric participants \<12 years of age at the signing of the assent (parent/guardian sign the informed consent)
2. Asymptomatic household contact with exposure to an individual with a diagnosis of SARS-CoV-2 infection (index case). To be included in the study, participants must be randomized within 96 hours of collection of the index cases' positive SARS-COV-2 diagnostic test sample
3. Participant anticipates living in the same household with the index case until study day 29
4. Is judged by the investigator to be in good health based on medical history and physical examination at screening/baseline, including participants who are healthy or have a chronic, stable medical condition
5. Willing and able to comply with study visits and study-related procedures/assessments.
6. Provide informed consent signed by study participant or legally acceptable representative.

Key Exclusion Criteria:

1. History of prior positive SARS-CoV-2 RT-PCR test or positive SARS-CoV-2 serology test at any time before the screening
2. Participant has lived with individuals who have had previous SARS-CoV-2 infection or currently lives with individuals who have SARS-CoV-2 infection, with the exception of the index case(s), the first individual(s) known to be infected in the household
3. Active respiratory or non-respiratory symptoms consistent with COVID-19
4. History of respiratory illness with sign/symptoms of SARS-CoV-2 infection, in the opinion of the investigator, within the prior 6 months to screening
5. Nursing home resident
6. Any physical examination findings, and/or history of any illness, concomitant medications or recent live vaccines that, in the opinion of the study investigator, might confound the results of the study or pose an additional risk to the participant by their participation in the study

Note: Other protocol-defined Inclusion/ Exclusion criteria apply