Phase 3 Boosting Study for the SARS-CoV-2 rS Vaccine

This is an observer-blinded Phase 3 study to evaluate the safety and immunogenicity of a single booster dose of the Novavax severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) recombinant (r) spike (S) protein nanoparticle vaccine adjuvanted with Matrix-MTM (NVX-CoV2373) in adults previously vaccinated with the BBIBP-CorV vaccine. The study will enroll approximately1,000 participants \>18 years of age. All participants will be randomized in a 1:1 ratio to receive a single booster dose of NVX-CoV2373 or the BBIBP-CorV vaccine. All participants will receive the booster dose on Day 0 and remain on study for immunogenicity and safety data collection through Day 180. An interim analysis will be performed of safety and immunogenicity data gathered through Day 28.

Novavax, Inc., is developing recombinant vaccines adjuvanted with the saponin-based Matrix-M for the prevention of disease caused by SARS-CoV-2. Both nonclinical and clinical data to date (Liu 2011; Keech 2020; Formica 2021; Heath 2021) support continued clinical development of SARS-CoV-2 rS vaccines combined with Matrix-M adjuvant as potential vaccines against SARS-CoV-2.

Due to waning immunity following primary vaccination against SARS-CoV-2 as well as the emergence of SARS-CoV-2 variants (eg, Alpha, Beta, Gamma, Delta and Omicron), a number of countries have administered or are planning to administer booster doses of vaccine to either specific subgroups or to their general population. As part of this effort, both homologous boosting (boosting with the same vaccine used for the primary vaccination series) or heterologous boosting (boosting with a vaccine that differs from that used for the primary vaccination series) are being evaluated.

The present study aims to investigate the safety and immunogenicity of a single booster of NVX-CoV2373 administered to participants who have already been immunized with BBIBP-CorV vaccine. The NVX-CoV2373 booster will be administered > 180 days after the second dose of BBIBP-CorV vaccine, and the ability of the vaccine to increase antibody titers against the prototype SARS-CoV-2 strain as well as the ability to induce cross-neutralizing antibodies to variant strains will be evaluated. If favorable immunogenicity and safety profiles are observed following a booster dose of NVX-CoV2373, this option would add flexibility to the global COVID-19 vaccination effort and potentially decrease the need to develop variant-specific vaccines.