Phase 3 Adolescent Study for SARS-CoV-2 rS Variant Vaccines

This is a Phase 3, randomized, double-blinded study to evaluate the safety and immunogenicity of booster doses of Omicron subvariant severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recombinant (r) spike (S) protein nanoparticle vaccines (SARS-CoV-2 rS) adjuvanted with Matrix-M™ adjuvant (NVX-CoV2601 \[Omicron XBB.1.5\]) and bivalent (NVX-CoV2373 \[prototype\] + NVX CoV2601) in previously vaccinated adolescent participants ≥ 12 to \< 18 years of age. Approximately 400 adolescents who have received a regimen of ≥ 2 doses of the Moderna and/or Pfizer-BioNTech monovalent and/or bivalent COVID-19 vaccines ≥ 90 days previously will be randomized 1:1 to Group A or Group B: * Group A: 1 dose of NVX-CoV2601 (1 on Day 0) * Group B: 1 dose of bivalent NVX-CoV2373 + NVX-CoV2601 (1 on Day 0) All participants will remain on study for immunogenicity and safety data collection through Day 180.