The mRNA-based Vaccine Candidate

mRNA based vaccines have contributed significantly to fight COVID-19. Two mRNA vaccines have already contributed to bringing the pandemic under control in some parts of the world. The global attention and willpower to bring to market new technology platforms has revolutionized the vaccine and public health landscape in the foreseeable future. But more will likely be needed to address variants of the virus, help control COVID-19 and expand the protection mRNA could offer in other disease areas. 

Sanofi’s scientists are developing an innovative mRNA-based COVID-19 vaccine, currently in phase 1/2 trials.

mRNA vaccine candidate: progress update

Sanofi and Translate Bio announced on March 12 the start of a phase 1/2 clinical trial for their mRNA COVID-19 vaccine candidate. The study will assess the vaccine candidate’s safety, immune response and reactogenicity with 415 participants to be enrolled across 13 investigational sites.

The joint development team is currently working on improving the temperature stability of the mRNA vaccine candidate to target a -20°C storage temperature for late-stage clinical trials and at launch. Efforts are also underway to enable the vaccine to remain stable at routine refrigerator temperature (2-8°C).

“Our mRNA vaccine candidate is the result of our expertise in infectious diseases coupled with the innovative technologies of our partner,” said Thomas Triomphe, Executive Vice President and Global Head of Sanofi Pasteur.

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

Rather than producing spike proteins in the lab, messenger RNA (mRNA) vaccines are designed to produce the desired antigens using the body's own protein-making machinery.1 Messenger RNA vaccines deliver instructions directly to a person's cells. When the cell carries out those instructions, they make just enough spike protein to stimulate the immune system to launch a fleet of antibodies to help fight it. Here's how the process works:

Discover how an mRNA vaccine is designed to work

Behind Sanofi’s mRNA Vaccine Candidate

Since 2018, Sanofi scientists have been working with Translate Bio, a clinical-stage biotechnology company that specializes in messenger RNA (mRNA) therapies, to design and develop an mRNA technology platform for vaccines.

How do Clinical Trials Work for our mRNA COVID-19 Vaccine Candidate?

When Sanofi’s vaccine teams seek to develop a new vaccine, they ask one simple question: Can the vaccine do what they expect it to do? A clinical trial aims to demonstrate that when our COVID-19 vaccine is given to people it meets the specific medical objectives that have been.


COVID-19 Frequently Asked Questions

Updates on our COVID-19 Vaccines


The Adjuvanted Recombinant Protein-based Vaccine Candidate


  1. Xu S, Yang K, Li R, Zhang L. mRNA Vaccine Era-Mechanisms, Drug Platform and Clinical Prospection. International Journal of Molecular Sciences. 2020 Sep;21(18). DOI: 10.3390/ijms21186582