The Adjuvanted Recombinant Protein-based Vaccine Candidate

Sanofi’s adjuvanted recombinant protein 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

Sanofi and GSK announced on May 27 the start of a pivotal phase 3 clinical trial for their COVID-19 recombinant vaccine candidate which, in phase 2 initial results shared May 17, demonstrated strong immune responses across all adult age groups. In parallel, Sanofi and GSK intend to conduct booster studies to assess the ability of a lower dose of the vaccine to generate a strong booster response regardless of the initial vaccine platform received. For more information, see our initial phase 2 results press release and phase 3 press release. Pending positive phase 3 outcomes and regulatory reviews, the vaccine is expected to be approved in the fourth quarter of 2021.

How is Sanofi’s candidate COVID-19 recombinant protein vaccine made? 

Sanofi’s recombinant protein COVID-19 vaccine candidate uses the same technology as one of Sanofi’s seasonal influenza vaccines. The new 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 the process works:

Discover how Sanofi's candidate recombinant protein vaccine is designed to work

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

When Sanofi teams seek to make a new vaccine, they look to answer one simple question: Can the vaccine do what they expect it to do? In other words, they 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

The mRNA-based Vaccine Candidate


  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).