Our Adjuvanted Recombinant Protein-based COVID-19 Vaccine Candidate

Our adjuvanted recombinant protein COVID-19 vaccine candidate is based on innovative and proven manufacturing technology. It is being developed in collaboration with the US BARDA and with GSK for its pandemic adjuvant platform.

Progress update

Timeline about the different phases of clinical trials for the COVID-19 recombinant vaccine candidate

On December 15th, Sanofi and GSK announced positive preliminary results of a study investigating the safety and immune response with their vaccine candidate as a booster regardless of primary vaccine received (mRNA or adenovirus vector based vaccines). 

Sanofi continues its ongoing phase 3 trial of the vaccine following a recommendation from the Data Safety and Monitoring Board (DSMB), an independent data oversight body.  The DSMB identified no safety concerns and recommended the trial continue into early 2022 to collect and provide the data necessary for regulatory submissions.

In addition to these clinical trials, recently published preclinical data indicated that the candidate vaccine has the potential to strongly boost immune responses following vaccination from many of the currently approved vaccines and against a broad range of variants. 

How is the recombinant protein vaccine made? 

Our recombinant protein COVID-19 vaccine candidate uses the SARS-CoV-2 virus spike protein as the vaccine antigen to help the body recognize and ideally fight off the real virus if a person becomes infected. The spike protein helps the coronavirus get into a person's cells, including those in the lungs.1 Here's how it works: 

Discover how our candidate recombinant protein vaccine is designed to work

How Clinical Trials Work for the Adjuvanted Recombinant protein COVID-19 vaccine candidate

When we seek to make a new vaccine, we look to answer one simple question: Can the vaccine do what we expect it to do? In other words, we aim to demonstrate that our COVID-19 vaccine meets the specific medical objectives set when given to the people who need it most. This is our process for study of our adjuvanted recombinant protein vaccine candidate.

Find out more about our Phase 2 BoosteR TRIAL   Find out more about our Phase 3 trial


COVID-19 Frequently Asked Questions

Updates on our COVID-19 Vaccines

Our Commitment to Fighting COVID-19


  1. Huang, Y., Yang, C., Xu, Xf. et al. Structural and functional properties of SARS-CoV-2 spike protein: potential antivirus drug development for COVID-19. Acta Pharmacol Sin 41, 1141–1149 (2020). https://doi.org/10.1038/s41401-020-0485-4